diff --git a/src/game/skills/druid-shapeshift.ts b/src/game/skills/druid-shapeshift.ts
new file mode 100644
index 0000000..424fb1d
--- /dev/null
+++ b/src/game/skills/druid-shapeshift.ts
@@ -0,0 +1,614 @@
+/**
+ * Diablo II: Lord of Destruction v1.13c — Druid Shape Shifting Skills Module
+ *
+ * Dedicated pure calculation, transformation states, charge-up orb progression,
+ * contagious spread, and kinematics formulas for the 10 Druid Shape Shifting Tree Skills:
+ * - Skill 223: Werewolf (ReqLevel 1)
+ * - Skill 224: Lycanthropy (ReqLevel 1)
+ * - Skill 228: Werebear (ReqLevel 6)
+ * - Skill 232: Feral Rage (ReqLevel 12)
+ * - Skill 233: Maul (ReqLevel 12)
+ * - Skill 238: Rabies (ReqLevel 18)
+ * - Skill 239: Fire Claws (ReqLevel 18)
+ * - Skill 242: Hunger (ReqLevel 24)
+ * - Skill 243: Shock Wave (ReqLevel 24)
+ * - Skill 248: Fury (ReqLevel 30)
+ *
+ * 1.13c Ground Truth:
+ * - Skills.txt, Missiles.txt, States.txt, Overlay.txt (Patch_D2.mpq)
+ * - Werewolf: attack rate dm(10, 80, slvl), attack rating, stamina, life, Lycanthropy duration
+ * - Lycanthropy: passive +20s/slvl shift duration, +20% base + 5%/slvl max HP
+ * - Werebear: enhanced physical damage 55% + 8%/slvl, armor bonus 25% + 6%/slvl, max HP 75% + Lycanthropy
+ * - Feral Rage: 3-stage charge orb, speed bonus dm(10, 70, slvl), life leech 4% * slvl
+ * - Maul: 5-stage charge orb, damage bonus 20% * slvl per charge, stun dm(10, 100, slvl)
+ * - Rabies: infectious poison bite spreading to adjacent targets within 4 subtiles
+ * - Fire Claws: massive elemental fire melee strike synergized by 4 elemental spells (+22%/blvl)
+ * - Hunger: dual life & mana leech dm(50, 200, slvl) with -75% damage penalty
+ * - Shock Wave: bear-only stun cone ln12 stun duration (40 frames + 15/slvl)
+ * - Fury: 5-hit uninterrupted feral frenzy sequence (min(2 + slvl - 1, 5) hits)
+ * - Zero runtime MPQ reading
+ */
+
+import { compute5BandScaling, computeDiminishingReturns } from '../engine/calc-ast.ts'
+
+// --- Skill IDs ---
+
+export const DRUID_SHAPESHIFT_SKILL_IDS = {
+  WEREWOLF: 223,
+  LYCANTHROPY: 224,
+  WEREBEAR: 228,
+  FERAL_RAGE: 232,
+  MAUL: 233,
+  RABIES: 238,
+  FIRE_CLAWS: 239,
+  HUNGER: 242,
+  SHOCK_WAVE: 243,
+  FURY: 248,
+} as const
+
+// --- Interfaces for Skill Calculations ---
+
+export interface WerewolfStats {
+  readonly attackRateBonusPct: number
+  readonly toHitBonusPct: number
+  readonly staminaBonusPct: number
+  readonly maxHpBonusPct: number
+  readonly durationFrames: number
+  readonly durationSeconds: number
+  readonly cooldownFrames: number
+  readonly cooldownSeconds: number
+  readonly manaCost: number
+  readonly manaCost256: number
+  readonly stateName: string
+}
+
+export interface LycanthropyStats {
+  readonly durationBonusFrames: number
+  readonly durationBonusSeconds: number
+  readonly maxHpBonusPct: number
+  readonly isPassive: boolean
+}
+
+export interface WerebearStats {
+  readonly damageBonusPct: number
+  readonly defenseBonusPct: number
+  readonly maxHpBonusPct: number
+  readonly durationFrames: number
+  readonly durationSeconds: number
+  readonly cooldownFrames: number
+  readonly cooldownSeconds: number
+  readonly manaCost: number
+  readonly manaCost256: number
+  readonly stateName: string
+}
+
+export interface FeralRageStats {
+  readonly damageBonusPct: number
+  readonly toHitBonusPct: number
+  readonly lifeLeechPct: number
+  readonly velocityBonusPct: number
+  readonly durationFrames: number
+  readonly durationSeconds: number
+  readonly maxCharges: number
+  readonly manaCost: number
+  readonly manaCost256: number
+  readonly stateName: string
+  readonly overlayName: string
+}
+
+export interface MaulStats {
+  readonly damageBonusPerChargePct: number
+  readonly maxDamageBonusPct: number
+  readonly toHitBonusPct: number
+  readonly stunDurationFrames: number
+  readonly stunDurationSeconds: number
+  readonly durationFrames: number
+  readonly durationSeconds: number
+  readonly maxCharges: number
+  readonly manaCost: number
+  readonly manaCost256: number
+  readonly stateName: string
+  readonly overlayName: string
+}
+
+export interface RabiesStats {
+  readonly minPoisonDamage: number
+  readonly maxPoisonDamage: number
+  readonly poisonDurationFrames: number
+  readonly poisonDurationSeconds: number
+  readonly toHitBonusPct: number
+  readonly contagionRadiusSubtiles: number
+  readonly contagionSpreadIntervalFrames: number
+  readonly synergyBonusPct: number
+  readonly manaCost: number
+  readonly manaCost256: number
+  readonly overlayName: string
+}
+
+export interface FireClawsStats {
+  readonly minFireDamage: number
+  readonly maxFireDamage: number
+  readonly toHitBonusPct: number
+  readonly synergyBonusPct: number
+  readonly manaCost: number
+  readonly manaCost256: number
+}
+
+export interface HungerStats {
+  readonly damagePenaltyPct: number
+  readonly lifeLeechPct: number
+  readonly manaLeechPct: number
+  readonly toHitBonusPct: number
+  readonly manaCost: number
+  readonly manaCost256: number
+}
+
+export interface ShockWaveStats {
+  readonly minPhysicalDamage: number
+  readonly maxPhysicalDamage: number
+  readonly stunDurationFrames: number
+  readonly stunDurationSeconds: number
+  readonly synergyBonusPct: number
+  readonly cooldownFrames: number
+  readonly manaCost: number
+  readonly manaCost256: number
+  readonly missileName: string
+}
+
+export interface FuryStats {
+  readonly damageBonusPct: number
+  readonly toHitBonusPct: number
+  readonly attackCount: number
+  readonly isUninterruptible: boolean
+  readonly manaCost: number
+  readonly manaCost256: number
+}
+
+// --- Pure Calculation Functions ---
+
+/**
+ * Skill 223: Werewolf (Wearwolf)
+ * Ground Truth:
+ * - Attack Rate bonus: dm(10, 80, slvl)
+ * - ToHit: 50 + (slvl - 1) * 15
+ * - Stamina: 25% (constant)
+ * - Max HP: 25% base + Lycanthropy.ln34 (20 + (lycBlvl - 1) * 5)%
+ * - Duration: 1000 frames (40s) + Lycanthropy.ln12 (1000 + (lycBlvl - 1) * 500 frames)
+ * - Mana: 15, Cooldown: 25 frames (1.0s)
+ */
+export function calculateWerewolfStats(
+  slvl: number,
+  lycanthropyBlvl = 0,
+): WerewolfStats {
+  const lvl = Math.max(1, slvl)
+  const lycPts = Math.max(0, lycanthropyBlvl)
+
+  const attackRateBonusPct = computeDiminishingReturns(10, 80, lvl)
+  const toHitBonusPct = 50 + (lvl - 1) * 15
+
+  const lycHpBonus = lycPts > 0 ? 20 + (lycPts - 1) * 5 : 0
+  const maxHpBonusPct = 25 + lycHpBonus
+
+  const lycDurationBonus = lycPts > 0 ? 1000 + (lycPts - 1) * 500 : 0
+  const durationFrames = 1000 + lycDurationBonus
+
+  return {
+    attackRateBonusPct,
+    toHitBonusPct,
+    staminaBonusPct: 25,
+    maxHpBonusPct,
+    durationFrames,
+    durationSeconds: durationFrames / 25,
+    cooldownFrames: 25,
+    cooldownSeconds: 1.0,
+    manaCost: 15,
+    manaCost256: 3840,
+    stateName: 'wolf',
+  }
+}
+
+/**
+ * Skill 224: Lycanthropy (Shape Shifting)
+ * Ground Truth:
+ * - Passive skill
+ * - Duration bonus: 1000 + (slvl - 1) * 500 frames (+20s/lvl)
+ * - Max HP bonus: 20 + (slvl - 1) * 5 % (+20% base, +5%/lvl)
+ */
+export function calculateLycanthropyStats(slvl: number): LycanthropyStats {
+  const lvl = Math.max(1, slvl)
+  const durationBonusFrames = 1000 + (lvl - 1) * 500
+  const maxHpBonusPct = 20 + (lvl - 1) * 5
+
+  return {
+    durationBonusFrames,
+    durationBonusSeconds: durationBonusFrames / 25,
+    maxHpBonusPct,
+    isPassive: true,
+  }
+}
+
+/**
+ * Skill 228: Werebear (Wearbear)
+ * Ground Truth:
+ * - Enhanced Damage: 55 + (slvl - 1) * 8 %
+ * - Armor / Defense: 25 + (slvl - 1) * 6 %
+ * - Max HP: 75% base + Lycanthropy.ln34 (20 + (lycBlvl - 1) * 5)%
+ * - Duration: 1000 frames (40s) + Lycanthropy.ln12 (1000 + (lycBlvl - 1) * 500 frames)
+ * - Mana: 15, Cooldown: 25 frames (1.0s)
+ */
+export function calculateWerebearStats(
+  slvl: number,
+  lycanthropyBlvl = 0,
+): WerebearStats {
+  const lvl = Math.max(1, slvl)
+  const lycPts = Math.max(0, lycanthropyBlvl)
+
+  const damageBonusPct = 55 + (lvl - 1) * 8
+  const defenseBonusPct = 25 + (lvl - 1) * 6
+
+  const lycHpBonus = lycPts > 0 ? 20 + (lycPts - 1) * 5 : 0
+  const maxHpBonusPct = 75 + lycHpBonus
+
+  const lycDurationBonus = lycPts > 0 ? 1000 + (lycPts - 1) * 500 : 0
+  const durationFrames = 1000 + lycDurationBonus
+
+  return {
+    damageBonusPct,
+    defenseBonusPct,
+    maxHpBonusPct,
+    durationFrames,
+    durationSeconds: durationFrames / 25,
+    cooldownFrames: 25,
+    cooldownSeconds: 1.0,
+    manaCost: 15,
+    manaCost256: 3840,
+    stateName: 'bear',
+  }
+}
+
+/**
+ * Skill 232: Feral Rage
+ * Ground Truth:
+ * - Wolf-only attack
+ * - Damage: 50 + (slvl - 1) * 5 %
+ * - ToHit: 20 + (slvl - 1) * 10 %
+ * - Life Leech: 4 * slvl % (accumulates with charge levels 1..3)
+ * - Velocity: dm(10, 70, slvl) %
+ * - Duration: 500 frames (20.0s)
+ * - Mana: 3
+ */
+export function calculateFeralRageStats(slvl: number): FeralRageStats {
+  const lvl = Math.max(1, slvl)
+  const damageBonusPct = 50 + (lvl - 1) * 5
+  const toHitBonusPct = 20 + (lvl - 1) * 10
+  const lifeLeechPct = 4 * lvl
+  const velocityBonusPct = computeDiminishingReturns(10, 70, lvl)
+
+  return {
+    damageBonusPct,
+    toHitBonusPct,
+    lifeLeechPct,
+    velocityBonusPct,
+    durationFrames: 500,
+    durationSeconds: 20.0,
+    maxCharges: 3,
+    manaCost: 3,
+    manaCost256: 768,
+    stateName: 'feralrage',
+    overlayName: 'feralrage1front',
+  }
+}
+
+/**
+ * Skill 233: Maul
+ * Ground Truth:
+ * - Bear-only attack
+ * - Damage bonus per charge: slvl * 20 % (up to 5 charges = slvl * 100 %)
+ * - ToHit: 20 + (slvl - 1) * 10 %
+ * - Stun duration: dm(10, 100, slvl) frames
+ * - Duration: 500 frames (20.0s)
+ * - Mana: 3
+ */
+export function calculateMaulStats(slvl: number): MaulStats {
+  const lvl = Math.max(1, slvl)
+  const damageBonusPerChargePct = lvl * 20
+  const maxDamageBonusPct = lvl * 100
+  const toHitBonusPct = 20 + (lvl - 1) * 10
+  const stunDurationFrames = computeDiminishingReturns(10, 100, lvl)
+
+  return {
+    damageBonusPerChargePct,
+    maxDamageBonusPct,
+    toHitBonusPct,
+    stunDurationFrames,
+    stunDurationSeconds: Number((stunDurationFrames / 25).toFixed(2)),
+    durationFrames: 500,
+    durationSeconds: 20.0,
+    maxCharges: 5,
+    manaCost: 3,
+    manaCost256: 768,
+    stateName: 'maul',
+    overlayName: 'maul1front',
+  }
+}
+
+/**
+ * Skill 238: Rabies
+ * Ground Truth:
+ * - Wolf-only infectious bite
+ * - Poison damage: eMin=6 [4, 5, 7, 11, 16], eMax=14 [4, 5, 7, 11, 16]
+ * - Poison length: 100 + (slvl - 1) * 10 frames (4s + 0.4s/lvl)
+ * - ToHit: 50 + (slvl - 1) * 7 %
+ * - Synergy: +18% poison damage per blvl in Plague Poppy (Poison Creeper)
+ * - Contagion radius: 4 subtiles, spread cadence: every 4 frames
+ * - Mana: 10
+ */
+export function calculateRabiesStats(
+  slvl: number,
+  plaguePoppyBlvl = 0,
+): RabiesStats {
+  const lvl = Math.max(1, slvl)
+  const ppPts = Math.max(0, plaguePoppyBlvl)
+
+  const rawMin = compute5BandScaling(lvl, 6, 4, 5, 7, 11, 16)
+  const rawMax = compute5BandScaling(lvl, 14, 4, 5, 7, 11, 16)
+  const synergyBonusPct = ppPts * 18
+
+  const minPoisonDamage = Math.trunc((rawMin * (100 + synergyBonusPct)) / 100)
+  const maxPoisonDamage = Math.trunc((rawMax * (100 + synergyBonusPct)) / 100)
+  const poisonDurationFrames = 100 + (lvl - 1) * 10
+
+  return {
+    minPoisonDamage,
+    maxPoisonDamage,
+    poisonDurationFrames,
+    poisonDurationSeconds: poisonDurationFrames / 25,
+    toHitBonusPct: 50 + (lvl - 1) * 7,
+    contagionRadiusSubtiles: 4,
+    contagionSpreadIntervalFrames: 4,
+    synergyBonusPct,
+    manaCost: 10,
+    manaCost256: 2560,
+    overlayName: 'rabiesplague',
+  }
+}
+
+/**
+ * Skill 239: Fire Claws
+ * Ground Truth:
+ * - Usable in Wolf or Bear form
+ * - Fire damage: eMin=15 [8, 12, 20, 24, 30], eMax=20 [8, 12, 22, 26, 34]
+ * - ToHit: 50 + (slvl - 1) * 15 %
+ * - Synergies: +22% fire damage per blvl in Firestorm, Molten Boulder, Volcano, Eruption
+ * - Mana: 4
+ */
+export function calculateFireClawsStats(
+  slvl: number,
+  firestormBlvl = 0,
+  moltenBoulderBlvl = 0,
+  volcanoBlvl = 0,
+  eruptionBlvl = 0,
+): FireClawsStats {
+  const lvl = Math.max(1, slvl)
+  const synTotal =
+    Math.max(0, firestormBlvl) +
+    Math.max(0, moltenBoulderBlvl) +
+    Math.max(0, volcanoBlvl) +
+    Math.max(0, eruptionBlvl)
+
+  const rawMin = compute5BandScaling(lvl, 15, 8, 12, 20, 24, 30)
+  const rawMax = compute5BandScaling(lvl, 20, 8, 12, 22, 26, 34)
+  const synergyBonusPct = synTotal * 22
+
+  const minFireDamage = Math.trunc((rawMin * (100 + synergyBonusPct)) / 100)
+  const maxFireDamage = Math.trunc((rawMax * (100 + synergyBonusPct)) / 100)
+
+  return {
+    minFireDamage,
+    maxFireDamage,
+    toHitBonusPct: 50 + (lvl - 1) * 15,
+    synergyBonusPct,
+    manaCost: 4,
+    manaCost256: 1024,
+  }
+}
+
+/**
+ * Skill 242: Hunger
+ * Ground Truth:
+ * - Usable in Wolf or Bear form
+ * - Damage penalty: -75% weapon damage
+ * - Life Leech: dm(50, 200, slvl) %
+ * - Mana Leech: dm(50, 200, slvl) %
+ * - ToHit: 50 + (slvl - 1) * 10 %
+ * - Mana: 3
+ */
+export function calculateHungerStats(slvl: number): HungerStats {
+  const lvl = Math.max(1, slvl)
+  const leechPct = computeDiminishingReturns(50, 200, lvl)
+
+  return {
+    damagePenaltyPct: -75,
+    lifeLeechPct: leechPct,
+    manaLeechPct: leechPct,
+    toHitBonusPct: 50 + (lvl - 1) * 10,
+    manaCost: 3,
+    manaCost256: 768,
+  }
+}
+
+/**
+ * Skill 243: Shock Wave
+ * Ground Truth:
+ * - Bear-only frontal sonic roar
+ * - Phys damage: minDam=10 [3, 5, 7, 7, 7], maxDam=20 [3, 5, 7, 7, 7]
+ * - Stun duration: ln12 = 40 + (slvl - 1) * 15 frames (1.6s at slvl 1, +0.6s/lvl)
+ * - Synergy: +5% physical damage per blvl in Maul
+ * - Mana: 7
+ */
+export function calculateShockWaveStats(
+  slvl: number,
+  maulBlvl = 0,
+): ShockWaveStats {
+  const lvl = Math.max(1, slvl)
+  const maulPts = Math.max(0, maulBlvl)
+
+  const rawMin = compute5BandScaling(lvl, 10, 3, 5, 7, 7, 7)
+  const rawMax = compute5BandScaling(lvl, 20, 3, 5, 7, 7, 7)
+  const synergyBonusPct = maulPts * 5
+
+  const minPhysicalDamage = Math.trunc((rawMin * (100 + synergyBonusPct)) / 100)
+  const maxPhysicalDamage = Math.trunc((rawMax * (100 + synergyBonusPct)) / 100)
+  const stunDurationFrames = 40 + (lvl - 1) * 15
+
+  return {
+    minPhysicalDamage,
+    maxPhysicalDamage,
+    stunDurationFrames,
+    stunDurationSeconds: stunDurationFrames / 25,
+    synergyBonusPct,
+    cooldownFrames: 0,
+    manaCost: 7,
+    manaCost256: 1792,
+    missileName: 'shockwave',
+  }
+}
+
+/**
+ * Skill 248: Fury
+ * Ground Truth:
+ * - Wolf-only rapid multi-attack sequence
+ * - Enhanced Damage: 100 + (slvl - 1) * 17 %
+ * - ToHit: 50 + (slvl - 1) * 7 %
+ * - Attack count: min(2 + slvl - 1, 5) hits
+ * - Uninterruptible sequence
+ * - Mana: 4
+ */
+export function calculateFuryStats(slvl: number): FuryStats {
+  const lvl = Math.max(1, slvl)
+  const damageBonusPct = 100 + (lvl - 1) * 17
+  const toHitBonusPct = 50 + (lvl - 1) * 7
+  const attackCount = Math.min(2 + lvl - 1, 5)
+
+  return {
+    damageBonusPct,
+    toHitBonusPct,
+    attackCount,
+    isUninterruptible: true,
+    manaCost: 4,
+    manaCost256: 1024,
+  }
+}
+
+// --- Kinematics & Mechanics Simulation Helpers ---
+
+/**
+ * Validates whether a given skill can be executed in the current Druid form.
+ */
+export function canCastShapeShiftSkill(
+  currentForm: 'human' | 'wolf' | 'bear',
+  skillId: number,
+): boolean {
+  switch (skillId) {
+    case DRUID_SHAPESHIFT_SKILL_IDS.WEREWOLF:
+      // Can cast if human (to transform into wolf) or wolf (to revert to human)
+      return currentForm === 'human' || currentForm === 'wolf'
+
+    case DRUID_SHAPESHIFT_SKILL_IDS.WEREBEAR:
+      // Can cast if human (to transform into bear) or bear (to revert to human)
+      return currentForm === 'human' || currentForm === 'bear'
+
+    case DRUID_SHAPESHIFT_SKILL_IDS.FERAL_RAGE:
+    case DRUID_SHAPESHIFT_SKILL_IDS.RABIES:
+    case DRUID_SHAPESHIFT_SKILL_IDS.FURY:
+      // Strictly Werewolf only
+      return currentForm === 'wolf'
+
+    case DRUID_SHAPESHIFT_SKILL_IDS.MAUL:
+    case DRUID_SHAPESHIFT_SKILL_IDS.SHOCK_WAVE:
+      // Strictly Werebear only
+      return currentForm === 'bear'
+
+    case DRUID_SHAPESHIFT_SKILL_IDS.FIRE_CLAWS:
+    case DRUID_SHAPESHIFT_SKILL_IDS.HUNGER:
+      // Can be used in either beast form, but not human
+      return currentForm === 'wolf' || currentForm === 'bear'
+
+    case DRUID_SHAPESHIFT_SKILL_IDS.LYCANTHROPY:
+      // Passive
+      return true
+
+    default:
+      return true
+  }
+}
+
+/**
+ * Advance charge-up orb counter on successful melee connection (Maul, Feral Rage).
+ */
+export function advanceChargeOrb(currentCharge: number, maxCharge: number): number {
+  return Math.min(Math.max(0, currentCharge) + 1, maxCharge)
+}
+
+export interface ContagionTarget {
+  readonly id: string
+  readonly x: number
+  readonly y: number
+}
+
+/**
+ * Simulate Rabies contagious spread between adjacent infected and healthy targets.
+ * Spread occurs within contagionRadiusSubtiles (default 4 subtiles = ~128px in world units).
+ */
+export function simulateRabiesContagion(
+  infectedTargets: readonly ContagionTarget[],
+  healthyTargets: readonly ContagionTarget[],
+  radiusPx = 128,
+): string[] {
+  const newlyInfectedIds: string[] = []
+
+  for (const healthy of healthyTargets) {
+    let infected = false
+    for (const source of infectedTargets) {
+      const dx = healthy.x - source.x
+      const dy = (healthy.y - source.y) * 2 // 2:1 isometric space
+      const distSq = dx * dx + dy * dy
+      if (distSq <= radiusPx * radiusPx) {
+        infected = true
+        break
+      }
+    }
+    if (infected) {
+      newlyInfectedIds.push(healthy.id)
+    }
+  }
+
+  return newlyInfectedIds
+}
+
+export interface FuryStrikeDistribution {
+  readonly targetId: string
+  readonly hitIndex: number
+}
+
+/**
+ * Distribute Fury multi-hit strike sequence across nearby target enemies.
+ * If 1 target, all strikes focus on that target. If multiple targets, alternates between them.
+ */
+export function distributeFuryStrikes(
+  targetIds: readonly string[],
+  totalHits: number,
+): FuryStrikeDistribution[] {
+  if (targetIds.length === 0 || totalHits <= 0) return []
+
+  const strikes: FuryStrikeDistribution[] = []
+  for (let i = 0; i < totalHits; i++) {
+    const targetId = targetIds[i % targetIds.length]!
+    strikes.push({
+      targetId,
+      hitIndex: i + 1,
+    })
+  }
+
+  return strikes
+}
diff --git a/tests/skills/dru/adv-dru-shapeshift-stress.test.ts b/tests/skills/dru/adv-dru-shapeshift-stress.test.ts
new file mode 100644
index 0000000..9db482f
--- /dev/null
+++ b/tests/skills/dru/adv-dru-shapeshift-stress.test.ts
@@ -0,0 +1,588 @@
+import { describe, expect, it } from 'vitest'
+import {
+  calculateWerewolfStats,
+  calculateLycanthropyStats,
+  calculateWerebearStats,
+  calculateFeralRageStats,
+  calculateMaulStats,
+  calculateRabiesStats,
+  calculateFireClawsStats,
+  calculateHungerStats,
+  calculateShockWaveStats,
+  calculateFuryStats,
+  canCastShapeShiftSkill,
+  advanceChargeOrb,
+  simulateRabiesContagion,
+  distributeFuryStrikes,
+  DRUID_SHAPESHIFT_SKILL_IDS,
+} from '../../../src/game/skills/druid-shapeshift.ts'
+import { BATCH1_SKILLS } from '../../../src/game/skills.ts'
+import { getSharedDataRegistry } from '../../../src/game/engine/data-registry.ts'
+import { UnitStatList } from '../../../src/game/engine/stat-list.ts'
+import { evaluateSkill113c } from '../../../src/game/skills/registry.ts'
+
+describe('Milestone M23 — Druid Shape Shifting Skills Parity & Adversarial Stress Suite', () => {
+  // =========================================================================
+  // Dimension 1: Exact 1.13c Numerical Scaling & Formulas
+  // =========================================================================
+  describe('Dimension 1: Exact 1.13c Numerical Scaling & Formulas', () => {
+    it('1.1 Werewolf (223): Evaluates attack rate diminishing returns, stamina, and Lycanthropy integration', () => {
+      // slvl 1 without Lycanthropy
+      const w1 = calculateWerewolfStats(1, 0)
+      expect(w1.attackRateBonusPct).toBe(21) // 10 + floor(110*1*70 / 700) = 21%
+      expect(w1.toHitBonusPct).toBe(50)
+      expect(w1.staminaBonusPct).toBe(25)
+      expect(w1.maxHpBonusPct).toBe(25) // 25 base
+      expect(w1.durationFrames).toBe(1000) // 40s base
+      expect(w1.durationSeconds).toBe(40.0)
+      expect(w1.cooldownFrames).toBe(25)
+      expect(w1.manaCost).toBe(15)
+      expect(w1.manaCost256).toBe(3840)
+
+      // slvl 10 with slvl 10 Lycanthropy
+      // attack rate: 10 + floor(110*10*70 / 1600) = 10 + 48 = 58%
+      // toHit: 50 + 9*15 = 185%
+      // lycHp: 20 + 9*5 = 65% -> total HP = 25 + 65 = 90%
+      // lycDuration: 1000 + 9*500 = 5500 -> total duration = 1000 + 5500 = 6500 frames (260s)
+      const w10 = calculateWerewolfStats(10, 10)
+      expect(w10.attackRateBonusPct).toBe(58)
+      expect(w10.toHitBonusPct).toBe(185)
+      expect(w10.maxHpBonusPct).toBe(90)
+      expect(w10.durationFrames).toBe(6500)
+      expect(w10.durationSeconds).toBe(260.0)
+
+      // slvl 20 with slvl 20 Lycanthropy
+      // attack rate: 10 + floor(110*20*70 / 2600) = 10 + 59 = 69%
+      // toHit: 50 + 19*15 = 335%
+      // lycHp: 20 + 19*5 = 115% -> total HP = 25 + 115 = 140%
+      // lycDuration: 1000 + 19*500 = 10500 -> total duration = 1000 + 10500 = 11500 frames (460s)
+      const w20 = calculateWerewolfStats(20, 20)
+      expect(w20.attackRateBonusPct).toBe(69)
+      expect(w20.toHitBonusPct).toBe(335)
+      expect(w20.maxHpBonusPct).toBe(140)
+      expect(w20.durationFrames).toBe(11500)
+      expect(w20.durationSeconds).toBe(460.0)
+    })
+
+    it('1.2 Lycanthropy (224): Evaluates passive form duration bonus and maximum HP progression', () => {
+      // slvl 1
+      const lyc1 = calculateLycanthropyStats(1)
+      expect(lyc1.durationBonusFrames).toBe(1000) // +40s
+      expect(lyc1.durationBonusSeconds).toBe(40.0)
+      expect(lyc1.maxHpBonusPct).toBe(20)
+      expect(lyc1.isPassive).toBe(true)
+
+      // slvl 10
+      const lyc10 = calculateLycanthropyStats(10)
+      expect(lyc10.durationBonusFrames).toBe(1000 + 9 * 500) // 5500 frames (+220s)
+      expect(lyc10.durationBonusSeconds).toBe(220.0)
+      expect(lyc10.maxHpBonusPct).toBe(20 + 9 * 5) // 65%
+
+      // slvl 20
+      const lyc20 = calculateLycanthropyStats(20)
+      expect(lyc20.durationBonusFrames).toBe(1000 + 19 * 500) // 10500 frames (+420s)
+      expect(lyc20.durationBonusSeconds).toBe(420.0)
+      expect(lyc20.maxHpBonusPct).toBe(20 + 19 * 5) // 115%
+    })
+
+    it('1.3 Werebear (228): Evaluates massive defense, enhanced damage, and life scaling', () => {
+      // slvl 1 without Lycanthropy
+      const wb1 = calculateWerebearStats(1, 0)
+      expect(wb1.damageBonusPct).toBe(55)
+      expect(wb1.defenseBonusPct).toBe(25)
+      expect(wb1.maxHpBonusPct).toBe(75) // 75 base
+      expect(wb1.durationFrames).toBe(1000)
+      expect(wb1.durationSeconds).toBe(40.0)
+      expect(wb1.cooldownFrames).toBe(25)
+      expect(wb1.manaCost).toBe(15)
+
+      // slvl 10 with slvl 10 Lycanthropy
+      // damage: 55 + 9*8 = 127%
+      // defense: 25 + 9*6 = 79%
+      // hp: 75 + (20 + 9*5) = 75 + 65 = 140%
+      const wb10 = calculateWerebearStats(10, 10)
+      expect(wb10.damageBonusPct).toBe(127)
+      expect(wb10.defenseBonusPct).toBe(79)
+      expect(wb10.maxHpBonusPct).toBe(140)
+      expect(wb10.durationFrames).toBe(6500)
+
+      // slvl 20 with slvl 20 Lycanthropy
+      // damage: 55 + 19*8 = 207%
+      // defense: 25 + 19*6 = 139%
+      // hp: 75 + (20 + 19*5) = 75 + 115 = 190%
+      const wb20 = calculateWerebearStats(20, 20)
+      expect(wb20.damageBonusPct).toBe(207)
+      expect(wb20.defenseBonusPct).toBe(139)
+      expect(wb20.maxHpBonusPct).toBe(190)
+      expect(wb20.durationFrames).toBe(11500)
+    })
+
+    it('1.4 Feral Rage (232): Evaluates damage, attack rating, speed bonus, and life leech', () => {
+      // slvl 1
+      const fr1 = calculateFeralRageStats(1)
+      expect(fr1.damageBonusPct).toBe(50)
+      expect(fr1.toHitBonusPct).toBe(20)
+      expect(fr1.lifeLeechPct).toBe(4) // 4 * 1
+      expect(fr1.velocityBonusPct).toBe(19) // 10 + floor(110*1*60 / 700) = 19%
+      expect(fr1.durationFrames).toBe(500) // 20.0s
+      expect(fr1.maxCharges).toBe(3)
+      expect(fr1.manaCost).toBe(3)
+      expect(fr1.manaCost256).toBe(768)
+
+      // slvl 10
+      // damage: 50 + 9*5 = 95%
+      // toHit: 20 + 9*10 = 110%
+      // life leech: 4 * 10 = 40%
+      // velocity: 10 + floor(110*10*60 / 1600) = 10 + 41 = 51%
+      const fr10 = calculateFeralRageStats(10)
+      expect(fr10.damageBonusPct).toBe(95)
+      expect(fr10.toHitBonusPct).toBe(110)
+      expect(fr10.lifeLeechPct).toBe(40)
+      expect(fr10.velocityBonusPct).toBe(51)
+
+      // slvl 20
+      // damage: 50 + 19*5 = 145%
+      // toHit: 20 + 19*10 = 210%
+      // life leech: 4 * 20 = 80%
+      // velocity: 10 + floor(110*20*60 / 2600) = 10 + 50 = 60%
+      const fr20 = calculateFeralRageStats(20)
+      expect(fr20.damageBonusPct).toBe(145)
+      expect(fr20.toHitBonusPct).toBe(210)
+      expect(fr20.lifeLeechPct).toBe(80)
+      expect(fr20.velocityBonusPct).toBe(60)
+    })
+
+    it('1.5 Maul (233): Evaluates 5-stage charge damage and stun scaling', () => {
+      // slvl 1
+      const m1 = calculateMaulStats(1)
+      expect(m1.damageBonusPerChargePct).toBe(20) // 1 * 20
+      expect(m1.maxDamageBonusPct).toBe(100) // 5 charges = 100%
+      expect(m1.toHitBonusPct).toBe(20)
+      expect(m1.stunDurationFrames).toBe(24) // 10 + floor(110*1*90 / 700) = 24 frames (~0.96s)
+      expect(m1.maxCharges).toBe(5)
+      expect(m1.manaCost).toBe(3)
+
+      // slvl 10
+      // damage/charge: 10 * 20 = 200%, max 5 charges = 1000%
+      // toHit: 20 + 9*10 = 110%
+      // stun: 10 + floor(110*10*90 / 1600) = 10 + 61 = 71 frames (2.84s)
+      const m10 = calculateMaulStats(10)
+      expect(m10.damageBonusPerChargePct).toBe(200)
+      expect(m10.maxDamageBonusPct).toBe(1000)
+      expect(m10.toHitBonusPct).toBe(110)
+      expect(m10.stunDurationFrames).toBe(71)
+
+      // slvl 20
+      // damage/charge: 20 * 20 = 400%, max 5 charges = 2000%
+      // toHit: 20 + 19*10 = 210%
+      // stun: 10 + floor(110*20*90 / 2600) = 10 + 76 = 86 frames (3.44s)
+      const m20 = calculateMaulStats(20)
+      expect(m20.damageBonusPerChargePct).toBe(400)
+      expect(m20.maxDamageBonusPct).toBe(2000)
+      expect(m20.toHitBonusPct).toBe(210)
+      expect(m20.stunDurationFrames).toBe(86)
+    })
+
+    it('1.6 Rabies (238): Evaluates poison progression, duration, and Poison Creeper synergy', () => {
+      // slvl 1
+      const r1 = calculateRabiesStats(1, 0)
+      expect(r1.minPoisonDamage).toBe(6)
+      expect(r1.maxPoisonDamage).toBe(14)
+      expect(r1.poisonDurationFrames).toBe(100) // 4.0s
+      expect(r1.toHitBonusPct).toBe(50)
+      expect(r1.contagionRadiusSubtiles).toBe(4)
+      expect(r1.contagionSpreadIntervalFrames).toBe(4)
+      expect(r1.manaCost).toBe(10)
+
+      // slvl 10: min: 6 + 7*4 + 2*5 = 44, max: 14 + 7*4 + 2*5 = 52
+      // duration: 100 + 9*10 = 190 frames (7.6s)
+      // toHit: 50 + 9*7 = 113%
+      const r10 = calculateRabiesStats(10, 0)
+      expect(r10.minPoisonDamage).toBe(44)
+      expect(r10.maxPoisonDamage).toBe(52)
+      expect(r10.poisonDurationFrames).toBe(190)
+      expect(r10.toHitBonusPct).toBe(113)
+
+      // slvl 20: min: 44 + 6*5 + 4*7 = 102, max: 52 + 6*5 + 4*7 = 110
+      // duration: 100 + 19*10 = 290 frames (11.6s)
+      // toHit: 50 + 19*7 = 183%
+      const r20 = calculateRabiesStats(20, 0)
+      expect(r20.minPoisonDamage).toBe(102)
+      expect(r20.maxPoisonDamage).toBe(110)
+      expect(r20.poisonDurationFrames).toBe(290)
+      expect(r20.toHitBonusPct).toBe(183)
+
+      // Synergy: 20 points in Poison Creeper (+18%/blvl = +360%)
+      const r20Syn = calculateRabiesStats(20, 20)
+      expect(r20Syn.synergyBonusPct).toBe(360)
+      expect(r20Syn.minPoisonDamage).toBe(Math.trunc((102 * 460) / 100)) // 469
+      expect(r20Syn.maxPoisonDamage).toBe(Math.trunc((110 * 460) / 100)) // 506
+    })
+
+    it('1.7 Fire Claws (239): Evaluates elemental fire melee damage and 4-way synergy scaling', () => {
+      // slvl 1
+      const fc1 = calculateFireClawsStats(1, 0, 0, 0, 0)
+      expect(fc1.minFireDamage).toBe(15)
+      expect(fc1.maxFireDamage).toBe(20)
+      expect(fc1.toHitBonusPct).toBe(50)
+      expect(fc1.manaCost).toBe(4)
+
+      // slvl 10: min: 15 + 7*8 + 2*12 = 95, max: 20 + 7*8 + 2*12 = 100
+      const fc10 = calculateFireClawsStats(10, 0, 0, 0, 0)
+      expect(fc10.minFireDamage).toBe(95)
+      expect(fc10.maxFireDamage).toBe(100)
+
+      // slvl 20: min: 95 + 6*12 + 4*20 = 247, max: 100 + 6*12 + 4*22 = 260
+      const fc20 = calculateFireClawsStats(20, 0, 0, 0, 0)
+      expect(fc20.minFireDamage).toBe(247)
+      expect(fc20.maxFireDamage).toBe(260)
+
+      // Synergies: 20 in Firestorm, 20 in Molten Boulder, 20 in Volcano, 20 in Fissure
+      // total points = 80 -> synergy = 80 * 22% = +1760%
+      const fc20Syn = calculateFireClawsStats(20, 20, 20, 20, 20)
+      expect(fc20Syn.synergyBonusPct).toBe(1760)
+      expect(fc20Syn.minFireDamage).toBe(Math.trunc((247 * 1860) / 100)) // 4594
+      expect(fc20Syn.maxFireDamage).toBe(Math.trunc((260 * 1860) / 100)) // 4836
+    })
+
+    it('1.8 Hunger (242): Evaluates -75% damage penalty and dual life & mana leech', () => {
+      // slvl 1
+      // leech: 50 + floor(110*1*150 / 700) = 50 + 23 = 73%
+      const h1 = calculateHungerStats(1)
+      expect(h1.damagePenaltyPct).toBe(-75)
+      expect(h1.lifeLeechPct).toBe(73)
+      expect(h1.manaLeechPct).toBe(73)
+      expect(h1.toHitBonusPct).toBe(50)
+      expect(h1.manaCost).toBe(3)
+
+      // slvl 10: 50 + floor(110*10*150 / 1600) = 50 + 103 = 153%
+      const h10 = calculateHungerStats(10)
+      expect(h10.lifeLeechPct).toBe(153)
+      expect(h10.manaLeechPct).toBe(153)
+      expect(h10.toHitBonusPct).toBe(140)
+
+      // slvl 20: 50 + floor(110*20*150 / 2600) = 50 + 126 = 176%
+      const h20 = calculateHungerStats(20)
+      expect(h20.lifeLeechPct).toBe(176)
+      expect(h20.manaLeechPct).toBe(176)
+      expect(h20.toHitBonusPct).toBe(240)
+    })
+
+    it('1.9 Shock Wave (243): Evaluates bear frontal sonic stun cone and Maul synergy', () => {
+      // slvl 1
+      const sw1 = calculateShockWaveStats(1, 0)
+      expect(sw1.minPhysicalDamage).toBe(10)
+      expect(sw1.maxPhysicalDamage).toBe(20)
+      expect(sw1.stunDurationFrames).toBe(40) // 1.6s
+      expect(sw1.stunDurationSeconds).toBe(1.6)
+      expect(sw1.manaCost).toBe(7)
+      expect(sw1.missileName).toBe('shockwave')
+
+      // slvl 10: min: 10 + 7*3 + 2*5 = 41, max: 20 + 7*3 + 2*5 = 51
+      // stun: 40 + 9*15 = 175 frames (7.0s)
+      const sw10 = calculateShockWaveStats(10, 0)
+      expect(sw10.minPhysicalDamage).toBe(41)
+      expect(sw10.maxPhysicalDamage).toBe(51)
+      expect(sw10.stunDurationFrames).toBe(175)
+      expect(sw10.stunDurationSeconds).toBe(7.0)
+
+      // slvl 20: min: 41 + 6*5 + 4*7 = 99, max: 51 + 6*5 + 4*7 = 109
+      // stun: 40 + 19*15 = 325 frames (13.0s)
+      const sw20 = calculateShockWaveStats(20, 0)
+      expect(sw20.minPhysicalDamage).toBe(99)
+      expect(sw20.maxPhysicalDamage).toBe(109)
+      expect(sw20.stunDurationFrames).toBe(325)
+      expect(sw20.stunDurationSeconds).toBe(13.0)
+
+      // Synergy: 20 in Maul (+5%/lvl = +100%)
+      const sw20Syn = calculateShockWaveStats(20, 20)
+      expect(sw20Syn.synergyBonusPct).toBe(100)
+      expect(sw20Syn.minPhysicalDamage).toBe(99 * 2) // 198
+      expect(sw20Syn.maxPhysicalDamage).toBe(109 * 2) // 218
+    })
+
+    it('1.10 Fury (248): Evaluates 5-hit uninterrupted feral frenzy sequence', () => {
+      // slvl 1: min(2 + 0, 5) = 2 hits
+      const f1 = calculateFuryStats(1)
+      expect(f1.damageBonusPct).toBe(100)
+      expect(f1.toHitBonusPct).toBe(50)
+      expect(f1.attackCount).toBe(2)
+      expect(f1.isUninterruptible).toBe(true)
+      expect(f1.manaCost).toBe(4)
+
+      // slvl 2: min(2 + 1, 5) = 3 hits
+      const f2 = calculateFuryStats(2)
+      expect(f2.attackCount).toBe(3)
+
+      // slvl 3: min(2 + 2, 5) = 4 hits
+      const f3 = calculateFuryStats(3)
+      expect(f3.attackCount).toBe(4)
+
+      // slvl 4+: min(2 + 3, 5) = 5 hits (capped)
+      const f4 = calculateFuryStats(4)
+      expect(f4.attackCount).toBe(5)
+
+      // slvl 10: 100 + 9*17 = 253%, 50 + 9*7 = 113%
+      const f10 = calculateFuryStats(10)
+      expect(f10.damageBonusPct).toBe(253)
+      expect(f10.toHitBonusPct).toBe(113)
+      expect(f10.attackCount).toBe(5)
+
+      // slvl 20: 100 + 19*17 = 423%, 50 + 19*7 = 183%
+      const f20 = calculateFuryStats(20)
+      expect(f20.damageBonusPct).toBe(423)
+      expect(f20.toHitBonusPct).toBe(183)
+      expect(f20.attackCount).toBe(5)
+    })
+  })
+
+  // =========================================================================
+  // Dimension 2: Beast Form Restrictions & State Validation Matrix
+  // =========================================================================
+  describe('Dimension 2: Beast Form Restrictions & State Validation Matrix', () => {
+    it('2.1 Enforces Wolf-only skills: Feral Rage, Rabies, Fury', () => {
+      const wolfSkills = [
+        DRUID_SHAPESHIFT_SKILL_IDS.FERAL_RAGE,
+        DRUID_SHAPESHIFT_SKILL_IDS.RABIES,
+        DRUID_SHAPESHIFT_SKILL_IDS.FURY,
+      ]
+
+      for (const skillId of wolfSkills) {
+        expect(canCastShapeShiftSkill('wolf', skillId)).toBe(true)
+        expect(canCastShapeShiftSkill('human', skillId)).toBe(false)
+        expect(canCastShapeShiftSkill('bear', skillId)).toBe(false)
+      }
+    })
+
+    it('2.2 Enforces Bear-only skills: Maul, Shock Wave', () => {
+      const bearSkills = [
+        DRUID_SHAPESHIFT_SKILL_IDS.MAUL,
+        DRUID_SHAPESHIFT_SKILL_IDS.SHOCK_WAVE,
+      ]
+
+      for (const skillId of bearSkills) {
+        expect(canCastShapeShiftSkill('bear', skillId)).toBe(true)
+        expect(canCastShapeShiftSkill('human', skillId)).toBe(false)
+        expect(canCastShapeShiftSkill('wolf', skillId)).toBe(false)
+      }
+    })
+
+    it('2.3 Enforces dual-form beast skills: Fire Claws and Hunger', () => {
+      const dualSkills = [
+        DRUID_SHAPESHIFT_SKILL_IDS.FIRE_CLAWS,
+        DRUID_SHAPESHIFT_SKILL_IDS.HUNGER,
+      ]
+
+      for (const skillId of dualSkills) {
+        expect(canCastShapeShiftSkill('wolf', skillId)).toBe(true)
+        expect(canCastShapeShiftSkill('bear', skillId)).toBe(true)
+        expect(canCastShapeShiftSkill('human', skillId)).toBe(false)
+      }
+    })
+
+    it('2.4 Enforces transformation and reversion capabilities', () => {
+      // Werewolf: can cast in human (to become wolf) or wolf (to revert to human), but not bear
+      expect(canCastShapeShiftSkill('human', DRUID_SHAPESHIFT_SKILL_IDS.WEREWOLF)).toBe(true)
+      expect(canCastShapeShiftSkill('wolf', DRUID_SHAPESHIFT_SKILL_IDS.WEREWOLF)).toBe(true)
+      expect(canCastShapeShiftSkill('bear', DRUID_SHAPESHIFT_SKILL_IDS.WEREWOLF)).toBe(false)
+
+      // Werebear: can cast in human (to become bear) or bear (to revert to human), but not wolf
+      expect(canCastShapeShiftSkill('human', DRUID_SHAPESHIFT_SKILL_IDS.WEREBEAR)).toBe(true)
+      expect(canCastShapeShiftSkill('bear', DRUID_SHAPESHIFT_SKILL_IDS.WEREBEAR)).toBe(true)
+      expect(canCastShapeShiftSkill('wolf', DRUID_SHAPESHIFT_SKILL_IDS.WEREBEAR)).toBe(false)
+    })
+  })
+
+  // =========================================================================
+  // Dimension 3: Kinematics, Contagion & Multi-Hit Mechanics
+  // =========================================================================
+  describe('Dimension 3: Kinematics, Contagion & Multi-Hit Mechanics', () => {
+    it('3.1 Rabies: Contagion spreads to nearby targets within 4 subtiles and ignores distant targets', () => {
+      const infected = [{ id: 'target_0', x: 100, y: 100 }]
+      const healthy = [
+        { id: 'target_close_1', x: 120, y: 105 }, // ~22px away (inside 128px radius)
+        { id: 'target_close_2', x: 80, y: 95 },   // ~22px away (inside 128px radius)
+        { id: 'target_far', x: 400, y: 400 },      // ~424px away (outside 128px radius)
+      ]
+
+      const newlyInfected = simulateRabiesContagion(infected, healthy, 128)
+      expect(newlyInfected).toContain('target_close_1')
+      expect(newlyInfected).toContain('target_close_2')
+      expect(newlyInfected).not.toContain('target_far')
+    })
+
+    it('3.2 Maul & Feral Rage: Charge-up orb increments up to exact maximum charges', () => {
+      // Feral Rage caps at 3
+      let frCharge = 0
+      frCharge = advanceChargeOrb(frCharge, 3)
+      expect(frCharge).toBe(1)
+      frCharge = advanceChargeOrb(frCharge, 3)
+      expect(frCharge).toBe(2)
+      frCharge = advanceChargeOrb(frCharge, 3)
+      expect(frCharge).toBe(3)
+      frCharge = advanceChargeOrb(frCharge, 3)
+      expect(frCharge).toBe(3) // Capped at 3
+
+      // Maul caps at 5
+      let mCharge = 0
+      for (let i = 0; i < 10; i++) {
+        mCharge = advanceChargeOrb(mCharge, 5)
+      }
+      expect(mCharge).toBe(5) // Capped at 5
+    })
+
+    it('3.3 Fury: Distributes 5-hit sequence evenly across multiple targets or focuses single target', () => {
+      // Single target
+      const singleStrikes = distributeFuryStrikes(['boss_1'], 5)
+      expect(singleStrikes.length).toBe(5)
+      expect(singleStrikes.every((s) => s.targetId === 'boss_1')).toBe(true)
+      expect(singleStrikes.map((s) => s.hitIndex)).toEqual([1, 2, 3, 4, 5])
+
+      // 2 targets (alternating)
+      const dualStrikes = distributeFuryStrikes(['enemy_a', 'enemy_b'], 5)
+      expect(dualStrikes.length).toBe(5)
+      expect(dualStrikes.map((s) => s.targetId)).toEqual([
+        'enemy_a',
+        'enemy_b',
+        'enemy_a',
+        'enemy_b',
+        'enemy_a',
+      ])
+    })
+  })
+
+  // =========================================================================
+  // Dimension 4: Invariants, DataRegistry, and SkillModule Integration
+  // =========================================================================
+  describe('Dimension 4: Invariants, DataRegistry, and SkillModule Integration', () => {
+    it('4.1 BATCH1_SKILLS length invariant = 38 is strictly preserved', () => {
+      const batch1Keys = Object.keys(BATCH1_SKILLS)
+      expect(batch1Keys.length).toBe(38)
+    })
+
+    it('4.2 All 10 Druid Shape Shifting skills are properly defined in SkillModule architecture', async () => {
+      const shapeShiftIds = [223, 224, 228, 232, 233, 238, 239, 242, 243, 248]
+      const { skillModule: m223 } = await import('../../../src/game/skills/impl/dru/skill-223-wearwolf.ts')
+      const { skillModule: m224 } = await import('../../../src/game/skills/impl/dru/skill-224-shape-shifting.ts')
+      const { skillModule: m228 } = await import('../../../src/game/skills/impl/dru/skill-228-wearbear.ts')
+      const { skillModule: m232 } = await import('../../../src/game/skills/impl/dru/skill-232-feral-rage.ts')
+      const { skillModule: m233 } = await import('../../../src/game/skills/impl/dru/skill-233-maul.ts')
+      const { skillModule: m238 } = await import('../../../src/game/skills/impl/dru/skill-238-rabies.ts')
+      const { skillModule: m239 } = await import('../../../src/game/skills/impl/dru/skill-239-fire-claws.ts')
+      const { skillModule: m242 } = await import('../../../src/game/skills/impl/dru/skill-242-hunger.ts')
+      const { skillModule: m243 } = await import('../../../src/game/skills/impl/dru/skill-243-shock-wave.ts')
+      const { skillModule: m248 } = await import('../../../src/game/skills/impl/dru/skill-248-fury.ts')
+
+      const modules = [m223, m224, m228, m232, m233, m238, m239, m242, m243, m248]
+      for (let i = 0; i < shapeShiftIds.length; i++) {
+        const id = shapeShiftIds[i]
+        const mod = modules[i]
+        expect(mod).toBeDefined()
+        expect(mod.skillId).toBe(id)
+        expect(mod.charClass).toBe('dru')
+      }
+    })
+
+    it('4.3 DataRegistry loads all 10 Druid Shape Shifting skills from Patch_D2.mpq with exact attributes', async () => {
+      const reg = await getSharedDataRegistry('samples/d2')
+
+      // Werewolf
+      const ww = reg.getSkillById(223)
+      expect(ww).toBeDefined()
+      expect(ww!.name).toBe('Wearwolf')
+      expect(ww!.auraState).toBe('wolf')
+      expect(ww!.delay).toBe('25')
+
+      // Lycanthropy
+      const lyc = reg.getSkillById(224)
+      expect(lyc).toBeDefined()
+      expect(lyc!.name).toBe('Shape Shifting')
+      expect(lyc!.passive).toBe(true)
+
+      // Werebear
+      const wb = reg.getSkillById(228)
+      expect(wb).toBeDefined()
+      expect(wb!.name).toBe('Wearbear')
+      expect(wb!.auraState).toBe('bear')
+      expect(wb!.delay).toBe('25')
+
+      // Feral Rage
+      const fr = reg.getSkillById(232)
+      expect(fr).toBeDefined()
+      expect(fr!.name).toBe('Feral Rage')
+      expect(fr!.auraState).toBe('feralrage')
+
+      // Maul
+      const m = reg.getSkillById(233)
+      expect(m).toBeDefined()
+      expect(m!.name).toBe('Maul')
+      expect(m!.auraState).toBe('maul')
+
+      // Rabies
+      const r = reg.getSkillById(238)
+      expect(r).toBeDefined()
+      expect(r!.name).toBe('Rabies')
+      expect(r!.srvMissileA).toBe('rabiesplague')
+
+      // Fire Claws
+      const fc = reg.getSkillById(239)
+      expect(fc).toBeDefined()
+      expect(fc!.name).toBe('Fire Claws')
+      expect(fc!.eType).toBe('fire')
+
+      // Hunger
+      const h = reg.getSkillById(242)
+      expect(h).toBeDefined()
+      expect(h!.name).toBe('Hunger')
+
+      // Shock Wave
+      const sw = reg.getSkillById(243)
+      expect(sw).toBeDefined()
+      expect(sw!.name).toBe('Shock Wave')
+      expect(sw!.srvMissileA).toBe('shockwave')
+
+      // Fury
+      const f = reg.getSkillById(248)
+      expect(f).toBeDefined()
+      expect(f!.name).toBe('Fury')
+    })
+
+    it('4.4 evaluateSkill113c evaluates Druid Shape Shifting skills against StatList with exact attributes', async () => {
+      const reg = await getSharedDataRegistry('samples/d2')
+      const stats = new UnitStatList()
+
+      // Werewolf
+      const wwRes = evaluateSkill113c({
+        registry: reg,
+        skill: reg.getSkillById(223)!,
+        slvl: 1,
+        blvl: 1,
+        statList: stats,
+      })
+      expect(wwRes.manaCost).toBe(15)
+      expect(wwRes.cooldownFrames).toBe(25)
+
+      // Maul
+      const mRes = evaluateSkill113c({
+        registry: reg,
+        skill: reg.getSkillById(233)!,
+        slvl: 10,
+        blvl: 10,
+        statList: stats,
+      })
+      expect(mRes.manaCost).toBe(3)
+      expect(mRes.toHitBonusPct).toBe(110)
+
+      // Fury
+      const fRes = evaluateSkill113c({
+        registry: reg,
+        skill: reg.getSkillById(248)!,
+        slvl: 20,
+        blvl: 20,
+        statList: stats,
+      })
+      expect(fRes.manaCost).toBe(4)
+      expect(fRes.toHitBonusPct).toBe(183)
+    })
+  })
+})