diff --git a/tools/balance/sim-balance.mjs b/tools/balance/sim-balance.mjs
index f9ec7dd..8ac149e 100644
--- a/tools/balance/sim-balance.mjs
+++ b/tools/balance/sim-balance.mjs
@@ -29,6 +29,13 @@ export function shuffle(arr, rng) {
 
 // 공격 피해 공식 — Lua CalcPlayerAttack(힘·약화) + DealDamageToTarget(취약)과 동기화.
 // floor((base + str) * (weak>0 ? 0.75 : 1)) → floor(... * (vulnOnTarget>0 ? 1.5 : 1))
+// 보상 카드 등급 추첨 (Lua OfferReward 미러) — roll ∈ 1..100, normal 70 / unique 25 / legend 5
+export function rarityForRoll(roll) {
+  if (roll > 95) return 'legend';
+  if (roll > 70) return 'unique';
+  return 'normal';
+}
+
 export function calcAttack(base, str, weak, vulnOnTarget) {
   let dmg = base + str;
   if (weak > 0) dmg = Math.floor(dmg * 0.75);
diff --git a/tools/balance/sim-balance.test.mjs b/tools/balance/sim-balance.test.mjs
index ce837f0..d9130a1 100644
--- a/tools/balance/sim-balance.test.mjs
+++ b/tools/balance/sim-balance.test.mjs
@@ -1,9 +1,18 @@
 import { test } from 'node:test';
 import assert from 'node:assert/strict';
 import {
-  mulberry32, applyDamage, chooseAction, chooseTarget, simulateCombat, runBatch, calcAttack,
+  mulberry32, applyDamage, chooseAction, chooseTarget, simulateCombat, runBatch, calcAttack, rarityForRoll,
 } from './sim-balance.mjs';
 
+test('rarityForRoll: 70/25/5 경계 (Lua OfferReward 미러)', () => {
+  assert.equal(rarityForRoll(1), 'normal');
+  assert.equal(rarityForRoll(70), 'normal');
+  assert.equal(rarityForRoll(71), 'unique');
+  assert.equal(rarityForRoll(95), 'unique');
+  assert.equal(rarityForRoll(96), 'legend');
+  assert.equal(rarityForRoll(100), 'legend');
+});
+
 test('applyDamage: 방어 우선 차감 후 hp', () => {
   assert.deepEqual(applyDamage(80, 0, 10), { hp: 70, block: 0 });
   assert.deepEqual(applyDamage(80, 5, 10), { hp: 75, block: 0 });
diff --git a/tools/deck/gen-slaydeck.mjs b/tools/deck/gen-slaydeck.mjs
index cb3754a..d2e9db8 100644
--- a/tools/deck/gen-slaydeck.mjs
+++ b/tools/deck/gen-slaydeck.mjs
@@ -3999,9 +3999,20 @@ return pool`, [], 0, 'any'),
     method('OfferReward', `self:SetEntityEnabled("/ui/DefaultGroup/CardHand", false)
 self:SetEntityEnabled("/ui/DefaultGroup/DeckHud", false)
 local pool = self:CardPool()
+local byRarity = {}
+for _, id in ipairs(pool) do
+	local r = self.Cards[id].rarity or "normal"
+	if byRarity[r] == nil then byRarity[r] = {} end
+	table.insert(byRarity[r], id)
+end
 self.RewardChoices = {}
 for i = 1, 3 do
-	self.RewardChoices[i] = pool[math.random(1, #pool)]
+	local roll = math.random(1, 100)
+	local want = "normal"
+	if roll > 95 then want = "legend" elseif roll > 70 then want = "unique" end
+	local bucket = byRarity[want]
+	if bucket == nil or #bucket == 0 then bucket = pool end
+	self.RewardChoices[i] = bucket[math.random(1, #bucket)]
 	self:ApplyRewardVisual(i, self.RewardChoices[i])
 end
 local hud = _EntityService:GetEntityByPath("/ui/DefaultGroup/RewardHud")