diff --git a/tools/balance/sim-balance.mjs b/tools/balance/sim-balance.mjs
index 3cd2b2b..c783ac6 100644
--- a/tools/balance/sim-balance.mjs
+++ b/tools/balance/sim-balance.mjs
@@ -55,7 +55,8 @@ export function calcAttack(base, str, weak, vulnOnTarget) {
 }
 
 export function calcEnemyAttack(base, str, weak, vulnOnTarget, strengthLoss = 0) {
-  return calcAttack(base, Math.max(0, str - strengthLoss), weak, vulnOnTarget);
+  // Lua EnemyActStep 동기화: 힘 손실은 (value+str) 전체에서 차감(음수 힘 허용), 최종 calcAttack이 0 클램프.
+  return calcAttack(base, str - strengthLoss, weak, vulnOnTarget);
 }
 
 // 방어 우선 차감 후 hp 적용 → { hp, block }
@@ -721,7 +722,7 @@ export function simulateCombat(data, rng, stats) {
       const it = m.intents.length ? m.intents[Math.floor(rng() * m.intents.length)] : null;
       if (it) {
         if (it.kind === 'Attack') {
-          const atk = calcAttack(it.value, Math.max(0, m.str - enemyStrengthLossThisTurn), m.weak, pVuln);
+          const atk = calcEnemyAttack(it.value, m.str, m.weak, pVuln, enemyStrengthLossThisTurn);
           const beforeHp = pHp;
           let incoming = atk;
           if (pIntangible > 0 && incoming > 1) incoming = 1;
diff --git a/tools/balance/sim-balance.test.mjs b/tools/balance/sim-balance.test.mjs
index dabeab9..fe44e5e 100644
--- a/tools/balance/sim-balance.test.mjs
+++ b/tools/balance/sim-balance.test.mjs
@@ -895,6 +895,13 @@ test("calcEnemyAttack: enemyStrengthLossThisTurn reduces enemy attack damage", (
   assert.equal(calcEnemyAttack(10, 6, 0, 0, 0), 16);
 });
 
+test("calcEnemyAttack: 힘 손실이 base 아래로 공격을 낮춘다 (음수 힘, Lua 동기화)", () => {
+  // 적 str=0, loss=6 → 힘 -6 → 10-6=4. JS가 str을 0에서 클램프하면 10(버그). Lua는 전체에서 차감.
+  assert.equal(calcEnemyAttack(10, 0, 0, 0, 6), 4);
+  assert.equal(calcEnemyAttack(10, 3, 0, 0, 6), 7);
+  assert.equal(calcEnemyAttack(5, 0, 0, 0, 6), 0); // 5-6=-1 → 0 클램프
+});
+
 test("simulateCombat: repeatOnKill repeats an attack until no kill occurs", () => {
   const shared = {
     cards: {