diff --git a/edgehead/lib/director/situational/leroy_quits.dart b/edgehead/lib/director/situational/leroy_quits.dart
index e2c558bc0..a3b1347e5 100644
--- a/edgehead/lib/director/situational/leroy_quits.dart
+++ b/edgehead/lib/director/situational/leroy_quits.dart
@@ -28,3 +28,5 @@ final _leroyQuits = Rule(_id++, 2, true, (ApplicabilityContext c) {
     b.currentRoomName = 'bleeds_trader_hut';
   });
 });
+
+// TODO: leroy simply quits when being too long with Aren
diff --git a/edgehead/lib/src/fight/actions/disarm_kick.dart b/edgehead/lib/src/fight/actions/disarm_kick.dart
index 0b4225f15..04cc4c1fc 100644
--- a/edgehead/lib/src/fight/actions/disarm_kick.dart
+++ b/edgehead/lib/src/fight/actions/disarm_kick.dart
@@ -87,7 +87,7 @@ class DisarmKick extends EnemyTargetAction with CombatCommandPath {
   @override
   ReasonedSuccessChance getSuccessChance(
       Actor a, Simulation sim, WorldState world, Actor enemy) {
-    return getCombatMoveChance(a, enemy, 0.6, [
+    return getCombatMoveChance(a, enemy, 0.6, world.statefulRandomState, [
       const Modifier(50, CombatReason.dexterity),
       const Modifier(30, CombatReason.balance),
       const Bonus(90, CombatReason.targetHasAllEyesDisabled),
diff --git a/edgehead/lib/src/fight/actions/smack_with_harmless_item.dart b/edgehead/lib/src/fight/actions/smack_with_harmless_item.dart
index 583aa0ffe..c490d5b50 100644
--- a/edgehead/lib/src/fight/actions/smack_with_harmless_item.dart
+++ b/edgehead/lib/src/fight/actions/smack_with_harmless_item.dart
@@ -80,7 +80,7 @@ class SmackWithHarmlessItem extends EnemyTargetAction with CombatCommandPath {
   @override
   ReasonedSuccessChance getSuccessChance(
       Actor a, Simulation sim, WorldState world, Actor enemy) {
-    return getCombatMoveChance(a, enemy, 0.3, [
+    return getCombatMoveChance(a, enemy, 0.3, world.statefulRandomState, [
       const Modifier(50, CombatReason.dexterity),
       const Modifier(30, CombatReason.balance),
       const Bonus(40, CombatReason.targetHasAllEyesDisabled),
diff --git a/edgehead/lib/src/fight/actions/start_bite.dart b/edgehead/lib/src/fight/actions/start_bite.dart
index b1efc2fd1..46a7ea070 100644
--- a/edgehead/lib/src/fight/actions/start_bite.dart
+++ b/edgehead/lib/src/fight/actions/start_bite.dart
@@ -31,7 +31,7 @@ ReasonedSuccessChance computeStartBiteAtBodyPartGenerator(
       math.max(bodyPart.swingSurfaceLeft, bodyPart.swingSurfaceRight) / 10, 1);
   final base = minBase + maxBase * relativeBiteSurface;
 
-  return getCombatMoveChance(a, enemy, base, [
+  return getCombatMoveChance(a, enemy, base, w.statefulRandomState, [
     const Modifier(30, CombatReason.dexterity),
     const Penalty(30, CombatReason.targetHasShield),
     const Modifier(30, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/actions/start_blunt_swing_at_head.dart b/edgehead/lib/src/fight/actions/start_blunt_swing_at_head.dart
index e95fb8746..8f5f20f2c 100644
--- a/edgehead/lib/src/fight/actions/start_blunt_swing_at_head.dart
+++ b/edgehead/lib/src/fight/actions/start_blunt_swing_at_head.dart
@@ -20,7 +20,7 @@ const String startBluntSwingAtHeadHelpMessage =
 
 ReasonedSuccessChance computeBluntSwingAtHeadPlayer(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.2, [
+  return getCombatMoveChance(a, enemy, 0.2, w.statefulRandomState, [
     const Modifier(30, CombatReason.dexterity),
     const Penalty(30, CombatReason.targetHasShield),
     const Modifier(20, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/actions/start_break_neck_on_ground.dart b/edgehead/lib/src/fight/actions/start_break_neck_on_ground.dart
index 64b8a4523..b1ac90cc4 100644
--- a/edgehead/lib/src/fight/actions/start_break_neck_on_ground.dart
+++ b/edgehead/lib/src/fight/actions/start_break_neck_on_ground.dart
@@ -17,7 +17,7 @@ const String startBreakNeckOnGroundHelpMessage =
 
 ReasonedSuccessChance computeBreakNeckOnGroundChance(
         Actor a, Simulation sim, WorldState w, Actor enemy) =>
-    getCombatMoveChance(a, enemy, 0.6, [
+    getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
       const Modifier(50, CombatReason.dexterity),
       ...disabledModifiers,
     ]);
diff --git a/edgehead/lib/src/fight/actions/start_clash.dart b/edgehead/lib/src/fight/actions/start_clash.dart
index a3355496d..bf2459d96 100644
--- a/edgehead/lib/src/fight/actions/start_clash.dart
+++ b/edgehead/lib/src/fight/actions/start_clash.dart
@@ -16,7 +16,7 @@ import 'package:edgehead/src/predetermined_result.dart';
 
 ReasonedSuccessChance computeStartClash(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.8, [
+  return getCombatMoveChance(a, enemy, 0.8, w.statefulRandomState, [
     const Modifier(95, CombatReason.dexterity),
     const Modifier(30, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/actions/start_crack_skull_on_ground.dart b/edgehead/lib/src/fight/actions/start_crack_skull_on_ground.dart
index 76cba6ec7..07d0f7b12 100644
--- a/edgehead/lib/src/fight/actions/start_crack_skull_on_ground.dart
+++ b/edgehead/lib/src/fight/actions/start_crack_skull_on_ground.dart
@@ -17,7 +17,7 @@ const String startCrackSkullOnGroundHelpMessage =
 
 ReasonedSuccessChance computeCrackSkullOnGroundChance(
         Actor a, Simulation sim, WorldState w, Actor enemy) =>
-    getCombatMoveChance(a, enemy, 0.6, [
+    getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
       const Modifier(50, CombatReason.dexterity),
       Penalty(a.currentDamageCapability.length >= 2 ? 40 : 90,
           CombatReason.targetHasWeapon),
diff --git a/edgehead/lib/src/fight/actions/start_feint_slash.dart b/edgehead/lib/src/fight/actions/start_feint_slash.dart
index f8fef1f06..71571bbe6 100644
--- a/edgehead/lib/src/fight/actions/start_feint_slash.dart
+++ b/edgehead/lib/src/fight/actions/start_feint_slash.dart
@@ -17,7 +17,7 @@ import 'package:meta/meta.dart';
 
 ReasonedSuccessChance computeStartFeint(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.8, const [
+  return getCombatMoveChance(a, enemy, 0.8, w.statefulRandomState, const [
     Modifier(95, CombatReason.dexterity),
     Modifier(50, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/actions/start_leap.dart b/edgehead/lib/src/fight/actions/start_leap.dart
index 371219351..1f2c50be3 100644
--- a/edgehead/lib/src/fight/actions/start_leap.dart
+++ b/edgehead/lib/src/fight/actions/start_leap.dart
@@ -17,7 +17,7 @@ const String startLeapHelpMessage =
 
 ReasonedSuccessChance computeStartLeap(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.2, [
+  return getCombatMoveChance(a, enemy, 0.2, w.statefulRandomState, [
     const Modifier(70, CombatReason.balance),
     const Modifier(50, CombatReason.height),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/actions/start_pull_down.dart b/edgehead/lib/src/fight/actions/start_pull_down.dart
index 79c7e3c08..582365322 100644
--- a/edgehead/lib/src/fight/actions/start_pull_down.dart
+++ b/edgehead/lib/src/fight/actions/start_pull_down.dart
@@ -16,7 +16,7 @@ import 'package:edgehead/src/predetermined_result.dart';
 
 ReasonedSuccessChance computeStartPullDown(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.05, [
+  return getCombatMoveChance(a, enemy, 0.05, w.statefulRandomState, [
     const Modifier(20, CombatReason.dexterity),
     const Modifier(10, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/actions/start_punch.dart b/edgehead/lib/src/fight/actions/start_punch.dart
index 9c52193ba..04fda532a 100644
--- a/edgehead/lib/src/fight/actions/start_punch.dart
+++ b/edgehead/lib/src/fight/actions/start_punch.dart
@@ -17,7 +17,7 @@ const String startPunchHelpMessage =
 
 ReasonedSuccessChance computeStartPunch(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.7, [
+  return getCombatMoveChance(a, enemy, 0.7, w.statefulRandomState, [
     const Modifier(75, CombatReason.dexterity),
     const Modifier(30, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/actions/start_punch_on_ground.dart b/edgehead/lib/src/fight/actions/start_punch_on_ground.dart
index 2b8df442c..b586778c3 100644
--- a/edgehead/lib/src/fight/actions/start_punch_on_ground.dart
+++ b/edgehead/lib/src/fight/actions/start_punch_on_ground.dart
@@ -17,7 +17,7 @@ const String startPunchOnGroundHelpMessage =
 
 ReasonedSuccessChance computeStartPunchOnGround(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.7, [
+  return getCombatMoveChance(a, enemy, 0.7, w.statefulRandomState, [
     const Modifier(75, CombatReason.dexterity),
     ...disabledModifiers,
   ]);
diff --git a/edgehead/lib/src/fight/actions/start_slash_at_body_part.dart b/edgehead/lib/src/fight/actions/start_slash_at_body_part.dart
index 611820a16..65c39c786 100644
--- a/edgehead/lib/src/fight/actions/start_slash_at_body_part.dart
+++ b/edgehead/lib/src/fight/actions/start_slash_at_body_part.dart
@@ -35,7 +35,7 @@ ReasonedSuccessChance computeStartSlashAtBodyPartGenerator(
       math.max(bodyPart.swingSurfaceLeft, bodyPart.swingSurfaceRight) / 10, 1);
   final base = minBase + maxBase * relativeSlashSurface;
 
-  return getCombatMoveChance(a, enemy, base, const [
+  return getCombatMoveChance(a, enemy, base, w.statefulRandomState, const [
     Modifier(30, CombatReason.dexterity),
     Modifier(30, CombatReason.balance),
     Modifier(30, CombatReason.weaponReach),
diff --git a/edgehead/lib/src/fight/actions/start_strike_down.dart b/edgehead/lib/src/fight/actions/start_strike_down.dart
index 029d2ca43..e4ca23f57 100644
--- a/edgehead/lib/src/fight/actions/start_strike_down.dart
+++ b/edgehead/lib/src/fight/actions/start_strike_down.dart
@@ -33,7 +33,7 @@ ReasonedSuccessChance computeStartStrikeDownPlayer(
       WeaponType.dagger.defaultLength;
   final base = (didRecentlyRoll ? 0.8 : 0.4) - (hasShortBlade ? 0.1 : 0);
 
-  return getCombatMoveChance(a, enemy, base, [
+  return getCombatMoveChance(a, enemy, base, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     const Penalty(30, CombatReason.targetHasShield),
     const Modifier(30, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/actions/start_sweep_feet.dart b/edgehead/lib/src/fight/actions/start_sweep_feet.dart
index 6d60c3aab..9c7c25ede 100644
--- a/edgehead/lib/src/fight/actions/start_sweep_feet.dart
+++ b/edgehead/lib/src/fight/actions/start_sweep_feet.dart
@@ -17,7 +17,7 @@ import 'package:edgehead/src/predetermined_result.dart';
 ReasonedSuccessChance computeStartSweepFeet(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
   assert(a.isPlayer);
-  return getCombatMoveChance(a, enemy, 0.6, [
+  return getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
     const Modifier(70, CombatReason.dexterity),
     const Modifier(70, CombatReason.balance),
     const Bonus(30, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/actions/start_throw_harmless.dart b/edgehead/lib/src/fight/actions/start_throw_harmless.dart
index e7774faa7..3183ec2de 100644
--- a/edgehead/lib/src/fight/actions/start_throw_harmless.dart
+++ b/edgehead/lib/src/fight/actions/start_throw_harmless.dart
@@ -17,7 +17,7 @@ const String startThrowHarmlessHelpMessage =
 
 ReasonedSuccessChance computeThrowHarmlessPlayer(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.2, [
+  return getCombatMoveChance(a, enemy, 0.2, w.statefulRandomState, [
     const Modifier(30, CombatReason.dexterity),
     const Penalty(30, CombatReason.targetHasShield),
     const Modifier(10, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/actions/start_throw_rock.dart b/edgehead/lib/src/fight/actions/start_throw_rock.dart
index 327d9c1e6..2f613ac2b 100644
--- a/edgehead/lib/src/fight/actions/start_throw_rock.dart
+++ b/edgehead/lib/src/fight/actions/start_throw_rock.dart
@@ -20,7 +20,7 @@ const String startThrowRockHelpMessage =
 
 ReasonedSuccessChance computeThrowRockPlayer(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.3, [
+  return getCombatMoveChance(a, enemy, 0.3, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     const Penalty(30, CombatReason.targetHasShield),
     const Modifier(20, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/actions/start_throw_thrusting_weapon.dart b/edgehead/lib/src/fight/actions/start_throw_thrusting_weapon.dart
index ca728d1fc..dffaedb10 100644
--- a/edgehead/lib/src/fight/actions/start_throw_thrusting_weapon.dart
+++ b/edgehead/lib/src/fight/actions/start_throw_thrusting_weapon.dart
@@ -25,7 +25,8 @@ ReasonedSuccessChance computeThrowThrustingWeaponPlayer(
   final hasDagger =
       a.currentWeapon?.damageCapability?.type == WeaponType.dagger ?? false;
   final hasThrowingWeapon = hasSpear || hasDagger;
-  return getCombatMoveChance(a, enemy, hasThrowingWeapon ? 0.3 : 0.01, [
+  return getCombatMoveChance(
+      a, enemy, hasThrowingWeapon ? 0.3 : 0.01, w.statefulRandomState, [
     Modifier(hasThrowingWeapon ? 20 : 10, CombatReason.dexterity),
     const Penalty(20, CombatReason.targetHasShield),
     Modifier(hasThrowingWeapon ? 20 : 10, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/actions/start_thrust.dart b/edgehead/lib/src/fight/actions/start_thrust.dart
index 918ae4049..4b1a96cb4 100644
--- a/edgehead/lib/src/fight/actions/start_thrust.dart
+++ b/edgehead/lib/src/fight/actions/start_thrust.dart
@@ -29,7 +29,7 @@ ReasonedSuccessChance computeThrustAtBodyPartChance(
   const maxBase = 0.6;
   final base = lerpDouble(bodyPart.thrustSurface, 0, 8, minBase, maxBase);
 
-  return getCombatMoveChance(a, enemy, base, [
+  return getCombatMoveChance(a, enemy, base, w.statefulRandomState, [
     const Modifier(30, CombatReason.dexterity),
     const Modifier(30, CombatReason.weaponReach),
     const Penalty(30, CombatReason.targetHasShield),
diff --git a/edgehead/lib/src/fight/actions/start_thrust_on_ground.dart b/edgehead/lib/src/fight/actions/start_thrust_on_ground.dart
index 58f2369b6..067ac4ed3 100644
--- a/edgehead/lib/src/fight/actions/start_thrust_on_ground.dart
+++ b/edgehead/lib/src/fight/actions/start_thrust_on_ground.dart
@@ -24,7 +24,7 @@ const String startThrustOnGroundHelpMessage =
 ReasonedSuccessChance computeStartThrustOnGroundPlayer(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
   assert(a.isPlayer);
-  return getCombatMoveChance(a, enemy, 0.5, [
+  return getCombatMoveChance(a, enemy, 0.5, w.statefulRandomState, [
     const Modifier(20, CombatReason.dexterity),
     const Penalty(60, CombatReason.targetHasShield),
     const Bonus(90, CombatReason.targetHasAllEyesDisabled),
diff --git a/edgehead/lib/src/fight/actions/wrestle_weapon_on_ground.dart b/edgehead/lib/src/fight/actions/wrestle_weapon_on_ground.dart
index 6e1e6c809..05edab1ab 100644
--- a/edgehead/lib/src/fight/actions/wrestle_weapon_on_ground.dart
+++ b/edgehead/lib/src/fight/actions/wrestle_weapon_on_ground.dart
@@ -113,7 +113,8 @@ class WrestleWeaponOnGround extends EnemyTargetAction with CombatCommandPath {
   @override
   ReasonedSuccessChance getSuccessChance(
       Actor a, Simulation sim, WorldState world, Actor enemy) {
-    return getCombatMoveChance(a, enemy, a.holdsSomeWeapon ? 0.2 : 0.4, [
+    return getCombatMoveChance(
+        a, enemy, a.holdsSomeWeapon ? 0.2 : 0.4, world.statefulRandomState, [
       const Modifier(50, CombatReason.dexterity),
       const Bonus(90, CombatReason.targetHasAllEyesDisabled),
     ]);
diff --git a/edgehead/lib/src/fight/bite/bite_defense/actions/dodge_bite.dart b/edgehead/lib/src/fight/bite/bite_defense/actions/dodge_bite.dart
index 34bf75dd2..40be5d64c 100644
--- a/edgehead/lib/src/fight/bite/bite_defense/actions/dodge_bite.dart
+++ b/edgehead/lib/src/fight/bite/bite_defense/actions/dodge_bite.dart
@@ -15,7 +15,7 @@ import 'package:edgehead/src/fight/fight_situation.dart';
 
 ReasonedSuccessChance computeDodgeBite(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.5, [
+  return getCombatMoveChance(a, enemy, 0.5, w.statefulRandomState, [
     const Modifier(60, CombatReason.dexterity),
     const Modifier(50, CombatReason.balance),
     const Bonus(50, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/bite/bite_defense/actions/impale_biter.dart b/edgehead/lib/src/fight/bite/bite_defense/actions/impale_biter.dart
index bdc717972..1457db514 100644
--- a/edgehead/lib/src/fight/bite/bite_defense/actions/impale_biter.dart
+++ b/edgehead/lib/src/fight/bite/bite_defense/actions/impale_biter.dart
@@ -213,7 +213,7 @@ class ImpaleBiter extends OtherActorAction {
   @override
   ReasonedSuccessChance getSuccessChance(
       Actor a, Simulation sim, WorldState w, Actor enemy) {
-    final chance = getCombatMoveChance(a, enemy, 0.3, [
+    final chance = getCombatMoveChance(a, enemy, 0.3, w.statefulRandomState, [
       const Modifier(40, CombatReason.dexterity),
       const Modifier(30, CombatReason.height),
       const Modifier(20, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/bite/bite_defense/actions/jump_back_from_bite.dart b/edgehead/lib/src/fight/bite/bite_defense/actions/jump_back_from_bite.dart
index 313927ded..c489e6c75 100644
--- a/edgehead/lib/src/fight/bite/bite_defense/actions/jump_back_from_bite.dart
+++ b/edgehead/lib/src/fight/bite/bite_defense/actions/jump_back_from_bite.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeJumpBackBite(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.9, [
+  return getCombatMoveChance(a, enemy, 0.9, w.statefulRandomState, [
     const Modifier(90, CombatReason.dexterity),
     const Modifier(10, CombatReason.balance),
     const Bonus(30, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/bite/bite_defense/actions/shield_block_bite.dart b/edgehead/lib/src/fight/bite/bite_defense/actions/shield_block_bite.dart
index b40bb5b0e..dfeb4dd78 100644
--- a/edgehead/lib/src/fight/bite/bite_defense/actions/shield_block_bite.dart
+++ b/edgehead/lib/src/fight/bite/bite_defense/actions/shield_block_bite.dart
@@ -13,7 +13,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeShieldBlockBite(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.6, [
+  return getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     const Modifier(30, CombatReason.balance),
     const Bonus(50, CombatReason.targetHasSecondaryArmDisabled),
diff --git a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/defensive_parry_blunt_swing.dart b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/defensive_parry_blunt_swing.dart
index eb5e809b8..4daf0d80d 100644
--- a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/defensive_parry_blunt_swing.dart
+++ b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/defensive_parry_blunt_swing.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeDefensiveParryBluntSwing(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.9, [
+  return getCombatMoveChance(a, enemy, 0.9, w.statefulRandomState, [
     const Modifier(95, CombatReason.dexterity),
     const Modifier(30, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/dodge_blunt_swing.dart b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/dodge_blunt_swing.dart
index da92d65d7..1088e5179 100644
--- a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/dodge_blunt_swing.dart
+++ b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/dodge_blunt_swing.dart
@@ -13,7 +13,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeDodgeBluntSwing(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.4, [
+  return getCombatMoveChance(a, enemy, 0.4, w.statefulRandomState, [
     const Modifier(60, CombatReason.dexterity),
     const Modifier(50, CombatReason.balance),
     const Bonus(50, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/jump_back_from_blunt_swing.dart b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/jump_back_from_blunt_swing.dart
index c6b1318c8..119891aa7 100644
--- a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/jump_back_from_blunt_swing.dart
+++ b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/jump_back_from_blunt_swing.dart
@@ -9,7 +9,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeJumpBackBluntSwing(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.9, [
+  return getCombatMoveChance(a, enemy, 0.9, w.statefulRandomState, [
     const Modifier(90, CombatReason.dexterity),
     const Modifier(10, CombatReason.balance),
     const Bonus(30, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/parry_blunt_swing.dart b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/parry_blunt_swing.dart
index 57ed90871..cb126d6a8 100644
--- a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/parry_blunt_swing.dart
+++ b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/parry_blunt_swing.dart
@@ -13,7 +13,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeParryBluntSwing(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.6, [
+  return getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     const Modifier(70, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/roll_away_from_blunt_swing.dart b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/roll_away_from_blunt_swing.dart
index 597276d5d..86fbafb91 100644
--- a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/roll_away_from_blunt_swing.dart
+++ b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/roll_away_from_blunt_swing.dart
@@ -10,7 +10,7 @@ import 'package:edgehead/src/fight/fight_situation.dart';
 
 ReasonedSuccessChance computeRollAwayFromBluntSwing(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.5, [
+  return getCombatMoveChance(a, enemy, 0.5, w.statefulRandomState, [
     const Modifier(90, CombatReason.dexterity),
     const Modifier(10, CombatReason.balance),
     const Bonus(20, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/shield_block_blunt_swing.dart b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/shield_block_blunt_swing.dart
index 3b86a1b02..d3ddc5366 100644
--- a/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/shield_block_blunt_swing.dart
+++ b/edgehead/lib/src/fight/blunt_swing/blunt_swing_defense/actions/shield_block_blunt_swing.dart
@@ -13,7 +13,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeShieldBlockBluntSwing(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.7, [
+  return getCombatMoveChance(a, enemy, 0.7, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     const Modifier(30, CombatReason.balance),
     const Bonus(50, CombatReason.targetHasSecondaryArmDisabled),
diff --git a/edgehead/lib/src/fight/clash/clash_defense/actions/counter_clash.dart b/edgehead/lib/src/fight/clash/clash_defense/actions/counter_clash.dart
index 921dddaf3..dcae65462 100644
--- a/edgehead/lib/src/fight/clash/clash_defense/actions/counter_clash.dart
+++ b/edgehead/lib/src/fight/clash/clash_defense/actions/counter_clash.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeCounterClash(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.2, const [
+  return getCombatMoveChance(a, enemy, 0.2, w.statefulRandomState, const [
     Modifier(20, CombatReason.dexterity),
     Modifier(20, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/common/conflict_chance.dart b/edgehead/lib/src/fight/common/conflict_chance.dart
index 325518930..0c56482b6 100644
--- a/edgehead/lib/src/fight/common/conflict_chance.dart
+++ b/edgehead/lib/src/fight/common/conflict_chance.dart
@@ -1,6 +1,9 @@
+import 'dart:math';
+
 import 'package:edgehead/fractal_stories/action.dart';
 import 'package:edgehead/fractal_stories/actor.dart';
 import 'package:edgehead/fractal_stories/anatomy/body_part.dart';
+import 'package:edgehead/stateful_random/stateful_random.dart';
 import 'package:meta/meta.dart';
 
 /// Modifiers applicable to most combat situations. These will make it easier
@@ -48,6 +51,9 @@ const List<CombatReason> reasonsRequiringPenalties = [
   CombatReason.targetHasShield,
 ];
 
+/// Used in [varyChance].
+final StatefulRandom _statefulRandom = StatefulRandom(42);
+
 /// This is a convenience method for constructing [ReasonedSuccessChance]
 /// for the combat in Edgehead.
 ///
@@ -63,7 +69,7 @@ const List<CombatReason> reasonsRequiringPenalties = [
 ///
 /// Example:
 ///
-///    return getCombatMoveChance(a, enemy, 0.5, [
+///    return getCombatMoveChance(a, enemy, 0.5, w.statefulRandomState, [
 ///      const Bonus(90, CombatReason.dexterity),
 ///      const Bonus(30, CombatReason.balance),
 ///    ]);
@@ -73,8 +79,16 @@ const List<CombatReason> reasonsRequiringPenalties = [
 /// stance. The difference in dexterity of the two actors can nudge
 /// the success chance almost all the way (`90`) up to 100%, or down to 0%. The
 /// combat stance can change the final success chance, too, but only by 30%.
-ReasonedSuccessChance<CombatReason> getCombatMoveChance(Actor performer,
-    Actor target, double base, List<Modifier<CombatReason>> modifiers) {
+///
+/// If [randomSeed] isn't `null`, then the combat chance will be varied
+/// according to [varyChance].
+ReasonedSuccessChance<CombatReason> getCombatMoveChance(
+  Actor performer,
+  Actor target,
+  double base,
+  int randomSeed,
+  List<Modifier<CombatReason>> modifiers,
+) {
   assert(base > 0.0, "For sureFailures, use ReasonedSuccessChance.sureFailure");
   assert(
       base < 1.0, "For sureSuccesses, use ReasonedSuccessChance.sureSuccess");
@@ -121,10 +135,56 @@ ReasonedSuccessChance<CombatReason> getCombatMoveChance(Actor performer,
     }
   }
 
+  if (randomSeed != null) {
+    value = varyChance(value, randomSeed);
+  }
+
   return ReasonedSuccessChance<CombatReason>(value,
       successReasons: successReasons, failureReasons: failureReasons);
 }
 
+/// Takes a chance [value] (from 0.0 to 1.0) and a [randomSeed], and varies
+/// the chance.
+@visibleForTesting
+double varyChance(double value, int randomSeed) {
+  assert(value >= 0.0);
+  assert(value <= 1.0);
+
+  /// The minimum distance between the resulting value and any of
+  /// the extremities (0 and 1).
+  const padding = 0.02;
+
+  if (value < padding || value > 1.0 - padding) return value;
+
+  // Set random according to the current state of the world.
+  _statefulRandom.loadState(randomSeed);
+
+  /// The max value change. For example, if initial value is 0.5, then
+  /// the resulting value must be 0.5 ± maxVariance.
+  const maxVariance = 0.3;
+
+  /// The max value change represented as a ratio of the distance between
+  /// the initial value and one of the extremities (0 or 1).
+  const scale = 0.7;
+
+  final distanceToClosestExtremity = min(
+    (value - 0.0).abs(),
+    (1.0 - value).abs(),
+  );
+
+  final scaledDistance = distanceToClosestExtremity * scale;
+  final clampedDistance = min(scaledDistance, maxVariance);
+
+  /// A random position on the scale from 0 to 2 times clamped distance
+  /// (from the value minus the distance to the value plus the distance,
+  /// so 2 distance in total).
+  final randomPosition = _statefulRandom.nextDouble() * clampedDistance * 2;
+
+  // The final number is the minimum (value minus distance) plus the random
+  // position.
+  return (value - clampedDistance) + randomPosition;
+}
+
 /// Returns the portion of body parts with given [function] that are disabled
 /// ([BodyPart.isAnimated] is `false`).
 ///
diff --git a/edgehead/lib/src/fight/counter_attack/actions/counter_blunt_swing.dart b/edgehead/lib/src/fight/counter_attack/actions/counter_blunt_swing.dart
index 1c99f7d15..a4d621c4d 100644
--- a/edgehead/lib/src/fight/counter_attack/actions/counter_blunt_swing.dart
+++ b/edgehead/lib/src/fight/counter_attack/actions/counter_blunt_swing.dart
@@ -20,7 +20,7 @@ const String counterBluntSwingHelpMessage =
 /// Will the actor be able to even execute the counter?
 ReasonedSuccessChance computeCounterBluntSwing(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.6, [
+  return getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     const Penalty(50, CombatReason.targetHasShield),
     const Modifier(50, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/counter_attack/actions/counter_slash.dart b/edgehead/lib/src/fight/counter_attack/actions/counter_slash.dart
index ca08fced4..9e25c6035 100644
--- a/edgehead/lib/src/fight/counter_attack/actions/counter_slash.dart
+++ b/edgehead/lib/src/fight/counter_attack/actions/counter_slash.dart
@@ -24,7 +24,7 @@ const String counterSlashHelpMessage =
 /// it lets the enemy defend (otherwise).
 ReasonedSuccessChance computeCounterSlash(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.6, [
+  return getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     // No weaponReach modifier. Counter slash can be effective even with
     // a short weapon.
diff --git a/edgehead/lib/src/fight/counter_attack/actions/counter_tackle.dart b/edgehead/lib/src/fight/counter_attack/actions/counter_tackle.dart
index 161582985..dbadc348b 100644
--- a/edgehead/lib/src/fight/counter_attack/actions/counter_tackle.dart
+++ b/edgehead/lib/src/fight/counter_attack/actions/counter_tackle.dart
@@ -12,7 +12,7 @@ import 'package:edgehead/src/fight/fight_situation.dart';
 
 ReasonedSuccessChance computeCounterTackle(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.5, [
+  return getCombatMoveChance(a, enemy, 0.5, w.statefulRandomState, [
     const Modifier(90, CombatReason.dexterity),
     const Modifier(50, CombatReason.balance),
     const Bonus(50, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/counter_attack/actions/counter_thrust.dart b/edgehead/lib/src/fight/counter_attack/actions/counter_thrust.dart
index 5012ec275..7ddc5e2c0 100644
--- a/edgehead/lib/src/fight/counter_attack/actions/counter_thrust.dart
+++ b/edgehead/lib/src/fight/counter_attack/actions/counter_thrust.dart
@@ -18,7 +18,7 @@ const String counterThrustHelpMessage =
 
 ReasonedSuccessChance computeCounterThrust(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.4, [
+  return getCombatMoveChance(a, enemy, 0.4, w.statefulRandomState, [
     const Modifier(30, CombatReason.dexterity),
     const Penalty(30, CombatReason.targetHasShield),
     const Modifier(30, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/counter_attack/actions/counter_thrust_on_ground.dart b/edgehead/lib/src/fight/counter_attack/actions/counter_thrust_on_ground.dart
index 0be16fd21..fe45d1d61 100644
--- a/edgehead/lib/src/fight/counter_attack/actions/counter_thrust_on_ground.dart
+++ b/edgehead/lib/src/fight/counter_attack/actions/counter_thrust_on_ground.dart
@@ -15,7 +15,7 @@ const String counterThrustOnGroundHelpMessage =
 
 ReasonedSuccessChance computeCounterThrustOnGround(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.4, [
+  return getCombatMoveChance(a, enemy, 0.4, w.statefulRandomState, [
     const Modifier(30, CombatReason.dexterity),
     const Penalty(30, CombatReason.targetHasShield),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/fatality_on_ground/wrestle_defense/actions/evade_on_ground.dart b/edgehead/lib/src/fight/fatality_on_ground/wrestle_defense/actions/evade_on_ground.dart
index 8ca0aa7b0..36edad966 100644
--- a/edgehead/lib/src/fight/fatality_on_ground/wrestle_defense/actions/evade_on_ground.dart
+++ b/edgehead/lib/src/fight/fatality_on_ground/wrestle_defense/actions/evade_on_ground.dart
@@ -10,7 +10,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeEvadeOnGroundChance(
         Actor a, Simulation sim, WorldState w, Actor enemy) =>
-    getCombatMoveChance(a, enemy, 0.6, [
+    getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
       const Modifier(50, CombatReason.dexterity),
       const Penalty(50, CombatReason.performerHasLimitedVision),
     ]);
diff --git a/edgehead/lib/src/fight/fatality_on_ground/wrestle_defense/actions/on_ground_parry_blunt.dart b/edgehead/lib/src/fight/fatality_on_ground/wrestle_defense/actions/on_ground_parry_blunt.dart
index 706250f3c..844fca018 100644
--- a/edgehead/lib/src/fight/fatality_on_ground/wrestle_defense/actions/on_ground_parry_blunt.dart
+++ b/edgehead/lib/src/fight/fatality_on_ground/wrestle_defense/actions/on_ground_parry_blunt.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeOnGroundParryBlunt(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.5, [
+  return getCombatMoveChance(a, enemy, 0.5, w.statefulRandomState, [
     const Modifier(70, CombatReason.dexterity),
     const Bonus(50, CombatReason.targetHasOneEyeDisabled),
     const Bonus(90, CombatReason.targetHasAllEyesDisabled),
diff --git a/edgehead/lib/src/fight/feint/feint_defense/actions/counter_feint.dart b/edgehead/lib/src/fight/feint/feint_defense/actions/counter_feint.dart
index d4ca77558..fb309eb29 100644
--- a/edgehead/lib/src/fight/feint/feint_defense/actions/counter_feint.dart
+++ b/edgehead/lib/src/fight/feint/feint_defense/actions/counter_feint.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/feint/feint_situation.dart';
 
 ReasonedSuccessChance computeCounterFeint(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.3, const [
+  return getCombatMoveChance(a, enemy, 0.3, w.statefulRandomState, const [
     Modifier(20, CombatReason.dexterity),
     Modifier(20, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/leap/leap_defense/actions/impale_leaper.dart b/edgehead/lib/src/fight/leap/leap_defense/actions/impale_leaper.dart
index 86efcb5fb..c43427fcf 100644
--- a/edgehead/lib/src/fight/leap/leap_defense/actions/impale_leaper.dart
+++ b/edgehead/lib/src/fight/leap/leap_defense/actions/impale_leaper.dart
@@ -125,7 +125,7 @@ class ImpaleLeaper extends EnemyTargetAction {
   @override
   ReasonedSuccessChance getSuccessChance(
       Actor a, Simulation sim, WorldState w, Actor enemy) {
-    final chance = getCombatMoveChance(a, enemy, 0.4, [
+    final chance = getCombatMoveChance(a, enemy, 0.4, w.statefulRandomState, [
       const Modifier(50, CombatReason.dexterity),
       const Modifier(30, CombatReason.height),
       const Modifier(20, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/leap/leap_defense/actions/swing_blunt_at_leaper.dart b/edgehead/lib/src/fight/leap/leap_defense/actions/swing_blunt_at_leaper.dart
index b47add065..792206ae2 100644
--- a/edgehead/lib/src/fight/leap/leap_defense/actions/swing_blunt_at_leaper.dart
+++ b/edgehead/lib/src/fight/leap/leap_defense/actions/swing_blunt_at_leaper.dart
@@ -153,7 +153,7 @@ class SwingBluntAtLeaper extends EnemyTargetAction {
   @override
   ReasonedSuccessChance getSuccessChance(
       Actor a, Simulation sim, WorldState w, Actor enemy) {
-    final chance = getCombatMoveChance(a, enemy, 0.2, [
+    final chance = getCombatMoveChance(a, enemy, 0.2, w.statefulRandomState, [
       const Modifier(40, CombatReason.dexterity),
       const Modifier(30, CombatReason.height),
       const Modifier(20, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/off_balance_opportunity/actions/off_balance_opportunity_thrust.dart b/edgehead/lib/src/fight/off_balance_opportunity/actions/off_balance_opportunity_thrust.dart
index 7c1c04669..53678bcbe 100644
--- a/edgehead/lib/src/fight/off_balance_opportunity/actions/off_balance_opportunity_thrust.dart
+++ b/edgehead/lib/src/fight/off_balance_opportunity/actions/off_balance_opportunity_thrust.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/common/humanoid_pain_or_death.dart';
 
 ReasonedSuccessChance computeOpportunityThrust(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.4, [
+  return getCombatMoveChance(a, enemy, 0.4, w.statefulRandomState, [
     const Modifier(20, CombatReason.dexterity),
     const Penalty(20, CombatReason.targetHasShield),
     const Modifier(20, CombatReason.balance),
diff --git a/edgehead/lib/src/fight/slash/slash_defense/actions/defensive_parry_slash.dart b/edgehead/lib/src/fight/slash/slash_defense/actions/defensive_parry_slash.dart
index a48e70362..e71b637e8 100644
--- a/edgehead/lib/src/fight/slash/slash_defense/actions/defensive_parry_slash.dart
+++ b/edgehead/lib/src/fight/slash/slash_defense/actions/defensive_parry_slash.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeDefensiveParrySlash(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.9, [
+  return getCombatMoveChance(a, enemy, 0.9, w.statefulRandomState, [
     const Modifier(95, CombatReason.dexterity),
     const Modifier(30, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/slash/slash_defense/actions/dodge_slash.dart b/edgehead/lib/src/fight/slash/slash_defense/actions/dodge_slash.dart
index 5273754e6..18ab87a67 100644
--- a/edgehead/lib/src/fight/slash/slash_defense/actions/dodge_slash.dart
+++ b/edgehead/lib/src/fight/slash/slash_defense/actions/dodge_slash.dart
@@ -13,7 +13,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeDodgeSlash(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.4, [
+  return getCombatMoveChance(a, enemy, 0.4, w.statefulRandomState, [
     const Modifier(60, CombatReason.dexterity),
     const Modifier(50, CombatReason.balance),
     const Bonus(50, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/slash/slash_defense/actions/jump_back.dart b/edgehead/lib/src/fight/slash/slash_defense/actions/jump_back.dart
index 5f837a776..fa8fd54cc 100644
--- a/edgehead/lib/src/fight/slash/slash_defense/actions/jump_back.dart
+++ b/edgehead/lib/src/fight/slash/slash_defense/actions/jump_back.dart
@@ -9,7 +9,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeJumpBackSlash(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.9, [
+  return getCombatMoveChance(a, enemy, 0.9, w.statefulRandomState, [
     const Modifier(90, CombatReason.dexterity),
     const Modifier(10, CombatReason.balance),
     const Bonus(30, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/slash/slash_defense/actions/parry_slash.dart b/edgehead/lib/src/fight/slash/slash_defense/actions/parry_slash.dart
index f7834131f..99fe678d6 100644
--- a/edgehead/lib/src/fight/slash/slash_defense/actions/parry_slash.dart
+++ b/edgehead/lib/src/fight/slash/slash_defense/actions/parry_slash.dart
@@ -13,7 +13,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeParrySlash(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.6, [
+  return getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     const Modifier(70, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/slash/slash_defense/actions/roll_back.dart b/edgehead/lib/src/fight/slash/slash_defense/actions/roll_back.dart
index f281795b3..057dc81f2 100644
--- a/edgehead/lib/src/fight/slash/slash_defense/actions/roll_back.dart
+++ b/edgehead/lib/src/fight/slash/slash_defense/actions/roll_back.dart
@@ -10,7 +10,7 @@ import 'package:edgehead/src/fight/fight_situation.dart';
 
 ReasonedSuccessChance computeRollBackSlash(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.4, [
+  return getCombatMoveChance(a, enemy, 0.4, w.statefulRandomState, [
     const Modifier(90, CombatReason.dexterity),
     const Modifier(10, CombatReason.balance),
     const Bonus(30, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/slash/slash_defense/actions/shield_block_slash.dart b/edgehead/lib/src/fight/slash/slash_defense/actions/shield_block_slash.dart
index 919ea5f39..767800d7c 100644
--- a/edgehead/lib/src/fight/slash/slash_defense/actions/shield_block_slash.dart
+++ b/edgehead/lib/src/fight/slash/slash_defense/actions/shield_block_slash.dart
@@ -13,7 +13,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeShieldBlockSlash(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.7, [
+  return getCombatMoveChance(a, enemy, 0.7, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     const Modifier(30, CombatReason.balance),
     const Bonus(50, CombatReason.targetHasSecondaryArmDisabled),
diff --git a/edgehead/lib/src/fight/slash_on_ground/slash_on_ground_defense/actions/dodge_slash_on_ground.dart b/edgehead/lib/src/fight/slash_on_ground/slash_on_ground_defense/actions/dodge_slash_on_ground.dart
index 4e5690b67..f92e103c0 100644
--- a/edgehead/lib/src/fight/slash_on_ground/slash_on_ground_defense/actions/dodge_slash_on_ground.dart
+++ b/edgehead/lib/src/fight/slash_on_ground/slash_on_ground_defense/actions/dodge_slash_on_ground.dart
@@ -12,7 +12,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeDodgeSlashOnGround(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.8, [
+  return getCombatMoveChance(a, enemy, 0.8, w.statefulRandomState, [
     const Modifier(30, CombatReason.dexterity),
     const Bonus(50, CombatReason.targetHasOneEyeDisabled),
     const Bonus(90, CombatReason.targetHasAllEyesDisabled),
diff --git a/edgehead/lib/src/fight/slash_on_ground/slash_on_ground_defense/actions/shield_block_slash_on_ground.dart b/edgehead/lib/src/fight/slash_on_ground/slash_on_ground_defense/actions/shield_block_slash_on_ground.dart
index 2fd3569e5..15fe66772 100644
--- a/edgehead/lib/src/fight/slash_on_ground/slash_on_ground_defense/actions/shield_block_slash_on_ground.dart
+++ b/edgehead/lib/src/fight/slash_on_ground/slash_on_ground_defense/actions/shield_block_slash_on_ground.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeShieldBlockSlashOnGround(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.9, [
+  return getCombatMoveChance(a, enemy, 0.9, w.statefulRandomState, [
     const Modifier(20, CombatReason.dexterity),
     const Bonus(70, CombatReason.targetHasOneEyeDisabled),
     const Bonus(90, CombatReason.targetHasAllEyesDisabled),
diff --git a/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/on_ground_parry.dart b/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/on_ground_parry.dart
index 510a58a07..ddf67b0a4 100644
--- a/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/on_ground_parry.dart
+++ b/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/on_ground_parry.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeOnGroundParry(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.5, [
+  return getCombatMoveChance(a, enemy, 0.5, w.statefulRandomState, [
     const Modifier(70, CombatReason.dexterity),
     const Bonus(50, CombatReason.targetHasOneEyeDisabled),
     const Bonus(90, CombatReason.targetHasAllEyesDisabled),
diff --git a/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/on_ground_shield_block.dart b/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/on_ground_shield_block.dart
index 5f0fc30b0..7a022f9f6 100644
--- a/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/on_ground_shield_block.dart
+++ b/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/on_ground_shield_block.dart
@@ -12,7 +12,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeOnGroundShieldBlock(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.7, [
+  return getCombatMoveChance(a, enemy, 0.7, w.statefulRandomState, [
     const Modifier(70, CombatReason.dexterity),
   ]);
 }
diff --git a/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/roll_out_of_way.dart b/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/roll_out_of_way.dart
index 20a569728..173def281 100644
--- a/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/roll_out_of_way.dart
+++ b/edgehead/lib/src/fight/strike_down/strike_down_defense/actions/roll_out_of_way.dart
@@ -14,7 +14,7 @@ ReasonedSuccessChance computeRollOutOfWay(
   final didRecentlyRoll = recentlyRolledOutOfWay(w, a);
   final base = didRecentlyRoll ? 0.3 : 0.9;
 
-  return getCombatMoveChance(a, enemy, base, [
+  return getCombatMoveChance(a, enemy, base, w.statefulRandomState, [
     const Modifier(70, CombatReason.dexterity),
     const Bonus(30, CombatReason.targetHasOneLegDisabled),
     const Bonus(90, CombatReason.targetHasAllLegsDisabled),
diff --git a/edgehead/lib/src/fight/strike_from_ground/strike_from_ground_defense/actions/jump_to_side_and_counter.dart b/edgehead/lib/src/fight/strike_from_ground/strike_from_ground_defense/actions/jump_to_side_and_counter.dart
index 386f8eefc..baa4d4821 100644
--- a/edgehead/lib/src/fight/strike_from_ground/strike_from_ground_defense/actions/jump_to_side_and_counter.dart
+++ b/edgehead/lib/src/fight/strike_from_ground/strike_from_ground_defense/actions/jump_to_side_and_counter.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/strike_from_ground/strike_from_ground_situati
 
 ReasonedSuccessChance computeJumpToSide(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.4, [
+  return getCombatMoveChance(a, enemy, 0.4, w.statefulRandomState, [
     const Modifier(60, CombatReason.dexterity),
     const Bonus(30, CombatReason.targetHasOneLegDisabled),
     const Bonus(50, CombatReason.targetHasAllLegsDisabled),
diff --git a/edgehead/lib/src/fight/strike_from_ground/strike_from_ground_defense/actions/step_back.dart b/edgehead/lib/src/fight/strike_from_ground/strike_from_ground_defense/actions/step_back.dart
index 56c3b3c1e..dc4f462e6 100644
--- a/edgehead/lib/src/fight/strike_from_ground/strike_from_ground_defense/actions/step_back.dart
+++ b/edgehead/lib/src/fight/strike_from_ground/strike_from_ground_defense/actions/step_back.dart
@@ -10,7 +10,7 @@ import 'package:edgehead/src/fight/strike_from_ground/strike_from_ground_situati
 
 ReasonedSuccessChance computeStepBack(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.7, [
+  return getCombatMoveChance(a, enemy, 0.7, w.statefulRandomState, [
     const Modifier(95, CombatReason.dexterity),
     const Bonus(30, CombatReason.targetHasOneLegDisabled),
     const Bonus(90, CombatReason.targetHasAllLegsDisabled),
diff --git a/edgehead/lib/src/fight/sweep_feet/sweep_feet_defense/actions/avoid_sweep_feet.dart b/edgehead/lib/src/fight/sweep_feet/sweep_feet_defense/actions/avoid_sweep_feet.dart
index cd9482fad..e03bf8aa8 100644
--- a/edgehead/lib/src/fight/sweep_feet/sweep_feet_defense/actions/avoid_sweep_feet.dart
+++ b/edgehead/lib/src/fight/sweep_feet/sweep_feet_defense/actions/avoid_sweep_feet.dart
@@ -10,7 +10,7 @@ import 'package:edgehead/src/fight/sweep_feet/sweep_feet_situation.dart';
 
 ReasonedSuccessChance computeAvoidSweep(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.7, const [
+  return getCombatMoveChance(a, enemy, 0.7, w.statefulRandomState, const [
     Modifier(30, CombatReason.dexterity),
     Modifier(20, CombatReason.balance),
     Bonus(30, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/sweep_feet/sweep_feet_defense/actions/counter_sweep_feet.dart b/edgehead/lib/src/fight/sweep_feet/sweep_feet_defense/actions/counter_sweep_feet.dart
index 6c9b85670..8c7735584 100644
--- a/edgehead/lib/src/fight/sweep_feet/sweep_feet_defense/actions/counter_sweep_feet.dart
+++ b/edgehead/lib/src/fight/sweep_feet/sweep_feet_defense/actions/counter_sweep_feet.dart
@@ -12,7 +12,7 @@ import 'package:edgehead/src/fight/sweep_feet/sweep_feet_situation.dart';
 
 ReasonedSuccessChance computeCounterSweepFeet(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.3, const [
+  return getCombatMoveChance(a, enemy, 0.3, w.statefulRandomState, const [
     Modifier(30, CombatReason.dexterity),
     Modifier(20, CombatReason.balance),
     ...disabledModifiers,
diff --git a/edgehead/lib/src/fight/throw/throw_defense/actions/catch_projectile.dart b/edgehead/lib/src/fight/throw/throw_defense/actions/catch_projectile.dart
index 7285e10a9..cf5e8d998 100644
--- a/edgehead/lib/src/fight/throw/throw_defense/actions/catch_projectile.dart
+++ b/edgehead/lib/src/fight/throw/throw_defense/actions/catch_projectile.dart
@@ -10,7 +10,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeCatchProjectile(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.05, [
+  return getCombatMoveChance(a, enemy, 0.05, w.statefulRandomState, [
     const Modifier(30, CombatReason.dexterity),
     const Penalty(30, CombatReason.performerHasLimitedVision),
   ]);
diff --git a/edgehead/lib/src/fight/throw/throw_defense/actions/dodge_throw.dart b/edgehead/lib/src/fight/throw/throw_defense/actions/dodge_throw.dart
index cea13ccef..43bd2495c 100644
--- a/edgehead/lib/src/fight/throw/throw_defense/actions/dodge_throw.dart
+++ b/edgehead/lib/src/fight/throw/throw_defense/actions/dodge_throw.dart
@@ -12,7 +12,7 @@ import 'package:edgehead/src/fight/throw/move_projectile_to_ground.dart';
 
 ReasonedSuccessChance computeDodgeThrow(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.6, [
+  return getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
     const Modifier(60, CombatReason.dexterity),
     const Modifier(30, CombatReason.balance),
     const Penalty(100, CombatReason.performerHasLimitedVision),
diff --git a/edgehead/lib/src/fight/throw/throw_defense/actions/shield_block_throw.dart b/edgehead/lib/src/fight/throw/throw_defense/actions/shield_block_throw.dart
index afbf49a3b..932c1ec58 100644
--- a/edgehead/lib/src/fight/throw/throw_defense/actions/shield_block_throw.dart
+++ b/edgehead/lib/src/fight/throw/throw_defense/actions/shield_block_throw.dart
@@ -13,7 +13,7 @@ import 'package:edgehead/src/fight/throw/move_projectile_to_ground.dart';
 
 ReasonedSuccessChance computeShieldBlockThrow(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.7, [
+  return getCombatMoveChance(a, enemy, 0.7, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     const Modifier(30, CombatReason.balance),
     const Penalty(100, CombatReason.performerHasLimitedVision),
diff --git a/edgehead/lib/src/fight/thrust/thrust_defense/actions/dodge_thrust.dart b/edgehead/lib/src/fight/thrust/thrust_defense/actions/dodge_thrust.dart
index db286c9c5..0a152c89a 100644
--- a/edgehead/lib/src/fight/thrust/thrust_defense/actions/dodge_thrust.dart
+++ b/edgehead/lib/src/fight/thrust/thrust_defense/actions/dodge_thrust.dart
@@ -13,7 +13,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeDodgeThrust(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.6, [
+  return getCombatMoveChance(a, enemy, 0.6, w.statefulRandomState, [
     const Modifier(60, CombatReason.dexterity),
     const Modifier(50, CombatReason.balance),
     const Bonus(50, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/thrust/thrust_defense/actions/jump_back.dart b/edgehead/lib/src/fight/thrust/thrust_defense/actions/jump_back.dart
index 94908bc4a..9feab6dcc 100644
--- a/edgehead/lib/src/fight/thrust/thrust_defense/actions/jump_back.dart
+++ b/edgehead/lib/src/fight/thrust/thrust_defense/actions/jump_back.dart
@@ -9,7 +9,7 @@ import 'package:edgehead/src/fight/common/defense_situation.dart';
 
 ReasonedSuccessChance computeJumpBackThrust(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.9, [
+  return getCombatMoveChance(a, enemy, 0.9, w.statefulRandomState, [
     const Modifier(90, CombatReason.dexterity),
     const Modifier(10, CombatReason.balance),
     const Bonus(30, CombatReason.targetHasOneLegDisabled),
diff --git a/edgehead/lib/src/fight/thrust/thrust_defense/actions/shield_block_thrust.dart b/edgehead/lib/src/fight/thrust/thrust_defense/actions/shield_block_thrust.dart
index 07dbb7f49..94ee49896 100644
--- a/edgehead/lib/src/fight/thrust/thrust_defense/actions/shield_block_thrust.dart
+++ b/edgehead/lib/src/fight/thrust/thrust_defense/actions/shield_block_thrust.dart
@@ -13,7 +13,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeShieldBlockThrust(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.7, [
+  return getCombatMoveChance(a, enemy, 0.7, w.statefulRandomState, [
     const Modifier(50, CombatReason.dexterity),
     const Modifier(30, CombatReason.balance),
     const Bonus(50, CombatReason.targetHasSecondaryArmDisabled),
diff --git a/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/dodge_thrust_on_ground.dart b/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/dodge_thrust_on_ground.dart
index d15e3ed43..c8fc38942 100644
--- a/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/dodge_thrust_on_ground.dart
+++ b/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/dodge_thrust_on_ground.dart
@@ -12,7 +12,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeDodgeThrustOnGround(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.8, [
+  return getCombatMoveChance(a, enemy, 0.8, w.statefulRandomState, [
     const Modifier(30, CombatReason.dexterity),
     const Bonus(50, CombatReason.targetHasOneEyeDisabled),
     const Bonus(90, CombatReason.targetHasAllEyesDisabled),
diff --git a/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/jump_over_thrust_on_ground.dart b/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/jump_over_thrust_on_ground.dart
index 5b9c68c71..6e4168d3f 100644
--- a/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/jump_over_thrust_on_ground.dart
+++ b/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/jump_over_thrust_on_ground.dart
@@ -12,7 +12,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeJumpOverThrustOnGround(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.9, [
+  return getCombatMoveChance(a, enemy, 0.9, w.statefulRandomState, [
     const Modifier(30, CombatReason.dexterity),
     const Bonus(50, CombatReason.targetHasOneEyeDisabled),
     const Bonus(90, CombatReason.targetHasAllEyesDisabled),
diff --git a/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/shield_block_thrust_on_ground.dart b/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/shield_block_thrust_on_ground.dart
index 52443d664..4368b20b7 100644
--- a/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/shield_block_thrust_on_ground.dart
+++ b/edgehead/lib/src/fight/thrust_on_ground/thrust_on_ground_defense/actions/shield_block_thrust_on_ground.dart
@@ -11,7 +11,7 @@ import 'package:edgehead/src/fight/counter_attack/counter_attack_situation.dart'
 
 ReasonedSuccessChance computeShieldBlockThrustOnGround(
     Actor a, Simulation sim, WorldState w, Actor enemy) {
-  return getCombatMoveChance(a, enemy, 0.9, [
+  return getCombatMoveChance(a, enemy, 0.9, w.statefulRandomState, [
     const Modifier(20, CombatReason.dexterity),
     const Bonus(70, CombatReason.targetHasOneEyeDisabled),
     const Bonus(90, CombatReason.targetHasAllEyesDisabled),
diff --git a/edgehead/test/conflict_chance_test.dart b/edgehead/test/conflict_chance_test.dart
index 51805181e..478bb4119 100644
--- a/edgehead/test/conflict_chance_test.dart
+++ b/edgehead/test/conflict_chance_test.dart
@@ -1,3 +1,5 @@
+import 'dart:math';
+
 import 'package:edgehead/fractal_stories/actor.dart';
 import 'package:edgehead/fractal_stories/pose.dart';
 import 'package:edgehead/src/fight/common/conflict_chance.dart';
@@ -11,7 +13,7 @@ void main() {
       Actor.initialized(1000, testRandomIdGetter, "goblin", dexterity: 100);
 
   test('player gets ~70% chance over goblin with a max50 dexterity roll', () {
-    final chance = getCombatMoveChance(aren, goblin, 0.6, [
+    final chance = getCombatMoveChance(aren, goblin, 0.6, null, [
       const Modifier(50, CombatReason.dexterity),
     ]);
 
@@ -19,7 +21,7 @@ void main() {
   });
 
   test('goblin gets ~45% chance over player with a max50 dexterity roll', () {
-    final chance = getCombatMoveChance(goblin, aren, 0.6, [
+    final chance = getCombatMoveChance(goblin, aren, 0.6, null, [
       const Modifier(50, CombatReason.dexterity),
     ]);
 
@@ -29,7 +31,7 @@ void main() {
   test('player gets ~50% chance over goblin when out of balance', () {
     final outOfBalanceAren = aren.rebuild((b) => b..pose = Pose.offBalance);
 
-    final chance = getCombatMoveChance(outOfBalanceAren, goblin, 0.6, [
+    final chance = getCombatMoveChance(outOfBalanceAren, goblin, 0.6, null, [
       const Modifier(50, CombatReason.dexterity),
       const Modifier(30, CombatReason.balance),
     ]);
@@ -39,7 +41,7 @@ void main() {
   });
 
   test('player gets ~90% chance over goblin with a max95 dex roll', () {
-    final chance = getCombatMoveChance(aren, goblin, 0.8, [
+    final chance = getCombatMoveChance(aren, goblin, 0.8, null, [
       const Modifier(95, CombatReason.dexterity),
     ]);
 
@@ -47,7 +49,7 @@ void main() {
   });
 
   test('goblin gets ~40% chance over player with a max95 dex roll', () {
-    final chance = getCombatMoveChance(goblin, aren, 0.8, [
+    final chance = getCombatMoveChance(goblin, aren, 0.8, null, [
       const Modifier(95, CombatReason.dexterity),
     ]);
 
@@ -58,7 +60,7 @@ void main() {
     final superman =
         Actor.initialized(111, testRandomIdGetter, "superman", dexterity: 999);
 
-    final chance = getCombatMoveChance(superman, goblin, 0.5, [
+    final chance = getCombatMoveChance(superman, goblin, 0.5, null, [
       const Modifier(50, CombatReason.dexterity),
     ]);
 
@@ -67,7 +69,7 @@ void main() {
 
   group('.inverted()', () {
     test('simple inversion with modifier', () {
-      final chance = getCombatMoveChance(aren, goblin, 0.8, [
+      final chance = getCombatMoveChance(aren, goblin, 0.8, null, [
         const Modifier(95, CombatReason.dexterity),
       ]);
 
@@ -78,7 +80,7 @@ void main() {
     test('inversion with two modifiers', () {
       var offBalanceGoblin = goblin.rebuild((b) => b..pose = Pose.offBalance);
 
-      final chance = getCombatMoveChance(aren, offBalanceGoblin, 0.8, [
+      final chance = getCombatMoveChance(aren, offBalanceGoblin, 0.8, null, [
         const Modifier(50, CombatReason.dexterity),
         const Modifier(50, CombatReason.balance),
       ]);
@@ -88,7 +90,7 @@ void main() {
     });
 
     test('inversion with modifier and bonus', () {
-      final chance = getCombatMoveChance(aren, goblin, 0.8, [
+      final chance = getCombatMoveChance(aren, goblin, 0.8, null, [
         const Modifier(50, CombatReason.dexterity),
         const Bonus(50, CombatReason.performerIsPlayer),
       ]);
@@ -113,4 +115,21 @@ void main() {
 
     expect(categorized, orderedEquals(all));
   });
+
+  group('varyChance', () {
+    final random = Random();
+
+    test('returns close to a high number', () {
+      expect(varyChance(0.85, random.nextInt(0xFFFFFF)), greaterThan(0.5));
+    });
+
+    test('returns close to a high number', () {
+      expect(varyChance(0.10, random.nextInt(0xFFFFFF)), lessThan(0.5));
+    });
+
+    test('does not go from middle completely to extremity', () {
+      expect(varyChance(0.50, random.nextInt(0xFFFFFF)), lessThan(0.9));
+      expect(varyChance(0.50, random.nextInt(0xFFFFFF)), greaterThan(0.1));
+    });
+  });
 }