diff --git a/app/game-api/package.json b/app/game-api/package.json
index 1e018e8..07a3f9f 100644
--- a/app/game-api/package.json
+++ b/app/game-api/package.json
@@ -18,6 +18,8 @@
         "worker:dev": "GAME_API_ROLE=battle-sim-worker tsdown -c ../../tsdown.config.ts -F @sammo-ts/game-api --watch",
         "worker:auction": "GAME_API_ROLE=auction-worker node dist/index.js",
         "worker:auction:dev": "GAME_API_ROLE=auction-worker tsdown -c ../../tsdown.config.ts -F @sammo-ts/game-api --watch",
+        "worker:tournament": "GAME_API_ROLE=tournament-worker node dist/index.js",
+        "worker:tournament:dev": "GAME_API_ROLE=tournament-worker tsdown -c ../../tsdown.config.ts -F @sammo-ts/game-api --watch",
         "lint": "eslint .",
         "lint:fix": "eslint . --fix",
         "test": "vitest run --config vitest.config.ts",
diff --git a/app/game-api/src/config.ts b/app/game-api/src/config.ts
index 6ba5c09..0b68bfa 100644
--- a/app/game-api/src/config.ts
+++ b/app/game-api/src/config.ts
@@ -14,6 +14,7 @@ export interface GameApiConfig {
     auctionTimerPollMs: number;
     auctionTimerResyncMs: number;
     auctionTimerRetentionSeconds: number;
+    tournamentPollMs: number;
     gameTokenSecret: string;
     flushChannel: string;
 }
@@ -62,6 +63,11 @@ export const resolveGameApiConfigFromEnv = (env: NodeJS.ProcessEnv = process.env
             21600,
             'AUCTION_TIMER_RETENTION_SECONDS'
         ),
+        tournamentPollMs: parseNumberWithFallback(
+            env.TOURNAMENT_POLL_MS,
+            1000,
+            'TOURNAMENT_POLL_MS'
+        ),
         gameTokenSecret: secret,
         flushChannel: `${gatewayPrefix}:flush`,
     };
diff --git a/app/game-api/src/index.ts b/app/game-api/src/index.ts
index 3e9da27..6aa5373 100644
--- a/app/game-api/src/index.ts
+++ b/app/game-api/src/index.ts
@@ -4,6 +4,7 @@ import { fileURLToPath } from 'node:url';
 import { runGameApiServer } from './server.js';
 import { runBattleSimWorker } from './battleSim/worker.js';
 import { runAuctionWorker } from './auction/worker.js';
+import { runTournamentWorker } from './tournament/worker.js';
 
 export * from './config.js';
 export * from './context.js';
@@ -26,6 +27,7 @@ export * from './auction/types.js';
 export * from './auction/keys.js';
 export * from './auction/scheduler.js';
 export * from './auction/worker.js';
+export * from './tournament/worker.js';
 
 // Types for TRPC consumer
 export type { MessageView } from './messages/store.js';
@@ -49,8 +51,10 @@ if (isMain()) {
         role === 'battle-sim-worker'
             ? runBattleSimWorker
             : role === 'auction-worker'
-              ? runAuctionWorker
-              : runGameApiServer;
+                            ? runAuctionWorker
+                            : role === 'tournament-worker'
+                                ? runTournamentWorker
+                                : runGameApiServer;
     run().catch((error) => {
         console.error('[game-api] failed to start', error);
         process.exitCode = 1;
diff --git a/app/game-api/src/tournament/keys.ts b/app/game-api/src/tournament/keys.ts
new file mode 100644
index 0000000..2caa186
--- /dev/null
+++ b/app/game-api/src/tournament/keys.ts
@@ -0,0 +1,11 @@
+export interface TournamentKeys {
+    stateKey: string;
+    participantsKey: string;
+    matchesKey: string;
+}
+
+export const buildTournamentKeys = (profileName: string): TournamentKeys => ({
+    stateKey: `sammo:${profileName}:tournament:state`,
+    participantsKey: `sammo:${profileName}:tournament:participants`,
+    matchesKey: `sammo:${profileName}:tournament:matches`,
+});
diff --git a/app/game-api/src/tournament/store.ts b/app/game-api/src/tournament/store.ts
new file mode 100644
index 0000000..1376de3
--- /dev/null
+++ b/app/game-api/src/tournament/store.ts
@@ -0,0 +1,46 @@
+import type { TournamentKeys } from './keys.js';
+import type { TournamentMatchEntry, TournamentParticipantEntry, TournamentState } from './types.js';
+
+interface RedisClientLike {
+    get(key: string): Promise<string | null>;
+    set(key: string, value: string): Promise<unknown>;
+}
+
+const safeJsonParse = <T>(raw: string | null): T | null => {
+    if (!raw) {
+        return null;
+    }
+    try {
+        return JSON.parse(raw) as T;
+    } catch {
+        return null;
+    }
+};
+
+export class TournamentStore {
+    constructor(private readonly redis: RedisClientLike, private readonly keys: TournamentKeys) {}
+
+    async getState(): Promise<TournamentState | null> {
+        return safeJsonParse<TournamentState>(await this.redis.get(this.keys.stateKey));
+    }
+
+    async setState(state: TournamentState): Promise<void> {
+        await this.redis.set(this.keys.stateKey, JSON.stringify(state));
+    }
+
+    async getParticipants(): Promise<TournamentParticipantEntry[]> {
+        return safeJsonParse<TournamentParticipantEntry[]>(await this.redis.get(this.keys.participantsKey)) ?? [];
+    }
+
+    async setParticipants(participants: TournamentParticipantEntry[]): Promise<void> {
+        await this.redis.set(this.keys.participantsKey, JSON.stringify(participants));
+    }
+
+    async getMatches(): Promise<TournamentMatchEntry[]> {
+        return safeJsonParse<TournamentMatchEntry[]>(await this.redis.get(this.keys.matchesKey)) ?? [];
+    }
+
+    async setMatches(matches: TournamentMatchEntry[]): Promise<void> {
+        await this.redis.set(this.keys.matchesKey, JSON.stringify(matches));
+    }
+}
diff --git a/app/game-api/src/tournament/types.ts b/app/game-api/src/tournament/types.ts
new file mode 100644
index 0000000..7f1e142
--- /dev/null
+++ b/app/game-api/src/tournament/types.ts
@@ -0,0 +1,34 @@
+import type { TournamentType } from '@sammo-ts/logic';
+
+export interface TournamentState {
+    stage: number;
+    phase: number;
+    type: TournamentType;
+    auto: boolean;
+    openYear: number;
+    openMonth: number;
+    termSeconds: number;
+    nextAt: string;
+    bettingId?: number;
+    lastError?: string;
+    lastErrorAt?: string;
+}
+
+export interface TournamentParticipantEntry {
+    id: number;
+    name: string;
+    leadership: number;
+    strength: number;
+    intel: number;
+    level: number;
+}
+
+export interface TournamentMatchEntry {
+    id: number;
+    stage: number;
+    roundIndex: number;
+    attackerId: number;
+    defenderId: number;
+    winnerId?: number;
+    log?: string[];
+}
diff --git a/app/game-api/src/tournament/worker.ts b/app/game-api/src/tournament/worker.ts
new file mode 100644
index 0000000..a16903e
--- /dev/null
+++ b/app/game-api/src/tournament/worker.ts
@@ -0,0 +1,171 @@
+import { resolveTournamentBattle } from '@sammo-ts/logic';
+import {
+    createGamePostgresConnector,
+    createRedisConnector,
+    resolvePostgresConfigFromEnv,
+    resolveRedisConfigFromEnv,
+} from '@sammo-ts/infra';
+
+import { resolveGameApiConfigFromEnv } from '../config.js';
+import { buildTournamentKeys } from './keys.js';
+import { TournamentStore } from './store.js';
+import type { TournamentMatchEntry, TournamentState } from './types.js';
+
+const sleepMs = (ms: number): Promise<void> => new Promise((resolve) => setTimeout(resolve, ms));
+
+const isBattleStage = (stage: number): boolean => stage >= 7 && stage <= 10;
+
+const nextStage = (stage: number): number => {
+    switch (stage) {
+        case 7:
+            return 8;
+        case 8:
+            return 9;
+        case 9:
+            return 10;
+        default:
+            return 0;
+    }
+};
+
+const resolveNextAt = (state: TournamentState): string =>
+    new Date(Date.now() + Math.max(1, state.termSeconds) * 1000).toISOString();
+
+const applyBattle = async (
+    store: TournamentStore,
+    state: TournamentState,
+    baseSeed: string
+): Promise<TournamentState> => {
+    const matches = await store.getMatches();
+    const participants = await store.getParticipants();
+
+    const pending = matches.filter((match) => match.stage === state.stage && !match.winnerId);
+    if (pending.length === 0) {
+        const next = nextStage(state.stage);
+        const nextState: TournamentState = {
+            ...state,
+            stage: next,
+            phase: 0,
+            nextAt: resolveNextAt(state),
+        };
+        await store.setState(nextState);
+        return nextState;
+    }
+
+    const target = pending[state.phase] ?? pending[0];
+    if (!target) {
+        throw new Error('토너먼트 매치가 없습니다.');
+    }
+
+    const attacker = participants.find((entry) => entry.id === target.attackerId);
+    const defender = participants.find((entry) => entry.id === target.defenderId);
+    if (!attacker || !defender) {
+        throw new Error('토너먼트 참가자 정보를 찾을 수 없습니다.');
+    }
+
+    const result = resolveTournamentBattle({
+        type: state.type,
+        battleType: 1,
+        attacker: {
+            id: attacker.id,
+            name: attacker.name,
+            stats: {
+                leadership: attacker.leadership,
+                strength: attacker.strength,
+                intel: attacker.intel,
+            },
+            level: attacker.level,
+        },
+        defender: {
+            id: defender.id,
+            name: defender.name,
+            stats: {
+                leadership: defender.leadership,
+                strength: defender.strength,
+                intel: defender.intel,
+            },
+            level: defender.level,
+        },
+        context: {
+            openYear: state.openYear,
+            openMonth: state.openMonth,
+            stage: state.stage,
+            phase: state.phase,
+            matchIndex: target.id,
+        },
+        baseSeed,
+    });
+
+    const updatedMatch: TournamentMatchEntry = {
+        ...target,
+        winnerId: result.winnerId ?? undefined,
+        log: result.log,
+    };
+
+    const nextMatches = matches.map((entry) => (entry.id === target.id ? updatedMatch : entry));
+    await store.setMatches(nextMatches);
+
+    const nextPhase = state.phase + 1;
+    const nextState: TournamentState = {
+        ...state,
+        phase: nextPhase,
+        nextAt: resolveNextAt(state),
+    };
+    await store.setState(nextState);
+    return nextState;
+};
+
+export const runTournamentWorker = async (): Promise<void> => {
+    const config = resolveGameApiConfigFromEnv();
+    const postgres = createGamePostgresConnector(resolvePostgresConfigFromEnv({ schema: config.profile }));
+    const redis = createRedisConnector(resolveRedisConfigFromEnv());
+
+    await postgres.connect();
+    await redis.connect();
+
+    const store = new TournamentStore(redis.client, buildTournamentKeys(config.profileName));
+
+    const handleExit = async () => {
+        await redis.disconnect();
+        await postgres.disconnect();
+    };
+    process.on('SIGINT', handleExit);
+    process.on('SIGTERM', handleExit);
+
+    while (true) {
+        const state = await store.getState();
+        if (!state || !state.auto) {
+            await sleepMs(config.tournamentPollMs);
+            continue;
+        }
+
+        if (!isBattleStage(state.stage)) {
+            await sleepMs(config.tournamentPollMs);
+            continue;
+        }
+
+        const nextAt = new Date(state.nextAt).getTime();
+        const now = Date.now();
+        if (Number.isFinite(nextAt) && nextAt > now) {
+            await sleepMs(Math.min(config.tournamentPollMs, nextAt - now));
+            continue;
+        }
+
+        try {
+            const worldState = await postgres.prisma.worldState.findFirst();
+            const baseSeed = (worldState?.meta as Record<string, unknown> | null)?.hiddenSeed ?? 'tournament';
+            await applyBattle(store, state, String(baseSeed));
+        } catch (error) {
+            const message = error instanceof Error ? error.message : 'Unknown error';
+            const nextState: TournamentState = {
+                ...state,
+                auto: false,
+                lastError: message,
+                lastErrorAt: new Date().toISOString(),
+            };
+            await store.setState(nextState);
+        }
+
+        await sleepMs(config.tournamentPollMs);
+    }
+};
diff --git a/app/game-engine/src/lifecycle/redisCommandStream.ts b/app/game-engine/src/lifecycle/redisCommandStream.ts
index 7886766..1eff2b7 100644
--- a/app/game-engine/src/lifecycle/redisCommandStream.ts
+++ b/app/game-engine/src/lifecycle/redisCommandStream.ts
@@ -210,6 +210,29 @@ const normalizeCommand = (envelope: TurnDaemonCommandEnvelope): TurnDaemonComman
                 officerLevel: command.officerLevel,
             };
         }
+        case 'tournamentRefund': {
+            if (!Array.isArray(command.refunds)) {
+                return null;
+            }
+            const refunds = command.refunds
+                .filter((entry) =>
+                    entry && typeof entry.generalId === 'number' && typeof entry.amount === 'number'
+                )
+                .map((entry) => ({
+                    generalId: entry.generalId,
+                    amount: entry.amount,
+                }));
+            if (refunds.length === 0) {
+                return null;
+            }
+            return {
+                type: 'tournamentRefund',
+                requestId: envelope.requestId,
+                bettingId: typeof command.bettingId === 'number' ? command.bettingId : undefined,
+                reason: typeof command.reason === 'string' ? command.reason : undefined,
+                refunds,
+            };
+        }
         case 'getStatus': {
             const requestId = typeof command.requestId === 'string' ? command.requestId : envelope.requestId;
             return { type: 'getStatus', requestId };
diff --git a/app/game-engine/src/turn/worldCommandHandler.ts b/app/game-engine/src/turn/worldCommandHandler.ts
index 86c7463..ce0ac17 100644
--- a/app/game-engine/src/turn/worldCommandHandler.ts
+++ b/app/game-engine/src/turn/worldCommandHandler.ts
@@ -451,6 +451,54 @@ async function handleAppoint(
     return { type: 'appoint', ok: true, generalId: command.generalId };
 }
 
+async function handleTournamentRefund(
+    ctx: CommandHandlerContext,
+    command: Extract<TurnDaemonCommand, { type: 'tournamentRefund' }>
+): Promise<TurnDaemonCommandResult> {
+    const { world, hooks } = ctx;
+    if (!command.refunds || command.refunds.length === 0) {
+        return {
+            type: 'tournamentRefund',
+            ok: false,
+            bettingId: command.bettingId,
+            reason: '환불 대상이 없습니다.',
+        };
+    }
+
+    let processed = 0;
+    let missing = 0;
+    let totalRefund = 0;
+
+    for (const refund of command.refunds) {
+        if (!refund || typeof refund.generalId !== 'number' || typeof refund.amount !== 'number') {
+            continue;
+        }
+        if (refund.amount <= 0) {
+            continue;
+        }
+        const general = world.getGeneralById(refund.generalId);
+        if (!general) {
+            missing += 1;
+            continue;
+        }
+        world.updateGeneral(refund.generalId, {
+            gold: general.gold + refund.amount,
+        });
+        processed += 1;
+        totalRefund += refund.amount;
+    }
+
+    await flushWorld(world, hooks);
+    return {
+        type: 'tournamentRefund',
+        ok: true,
+        bettingId: command.bettingId,
+        processed,
+        missing,
+        totalRefund,
+    };
+}
+
 export const createTurnDaemonCommandHandler = (options: {
     world: InMemoryTurnWorld;
     hooks?: TurnDaemonHooks;
@@ -485,6 +533,8 @@ export const createTurnDaemonCommandHandler = (options: {
                     return handleKick(ctx, command);
                 case 'appoint':
                     return handleAppoint(ctx, command);
+                case 'tournamentRefund':
+                    return handleTournamentRefund(ctx, command);
                 default:
                     return null;
             }
diff --git a/packages/common/src/index.ts b/packages/common/src/index.ts
index 738fe0f..f786bc6 100644
--- a/packages/common/src/index.ts
+++ b/packages/common/src/index.ts
@@ -8,6 +8,7 @@ export * from './util/JosaUtil.js';
 export * from './util/RNG.js';
 export * from './util/RandUtil.js';
 export * from './util/TestRNG.js';
+export * from './util/TournamentRNG.js';
 export * from './util/sha512.js';
 export * from './util/parse.js';
 export * from './turnDaemon/types.js';
diff --git a/packages/common/src/turnDaemon/types.ts b/packages/common/src/turnDaemon/types.ts
index f662a22..fde5a1d 100644
--- a/packages/common/src/turnDaemon/types.ts
+++ b/packages/common/src/turnDaemon/types.ts
@@ -85,7 +85,17 @@ export type TurnDaemonCommand =
           destGeneralId: number;
           destCityId: number;
           officerLevel: number;
-      };
+        }
+    | {
+                type: 'tournamentRefund';
+                requestId?: string;
+                bettingId?: number;
+                reason?: string;
+                refunds: Array<{
+                        generalId: number;
+                        amount: number;
+                }>;
+        };
 
 export type TurnDaemonCommandResult =
     | {
@@ -132,7 +142,21 @@ export type TurnDaemonCommandResult =
     | { type: 'dropItem'; ok: boolean; generalId: number; reason?: string }
     | { type: 'changePermission'; ok: boolean; generalId: number; reason?: string }
     | { type: 'kick'; ok: boolean; generalId: number; reason?: string }
-    | { type: 'appoint'; ok: boolean; generalId: number; reason?: string };
+    | { type: 'appoint'; ok: boolean; generalId: number; reason?: string }
+    | {
+          type: 'tournamentRefund';
+          ok: true;
+          bettingId?: number;
+          processed: number;
+          missing: number;
+          totalRefund: number;
+      }
+    | {
+          type: 'tournamentRefund';
+          ok: false;
+          bettingId?: number;
+          reason: string;
+      };
 
 export type TurnDaemonEvent =
     | { type: 'status'; requestId?: string; status: TurnDaemonStatus }
diff --git a/packages/common/src/util/TournamentRNG.ts b/packages/common/src/util/TournamentRNG.ts
new file mode 100644
index 0000000..6aec88c
--- /dev/null
+++ b/packages/common/src/util/TournamentRNG.ts
@@ -0,0 +1,37 @@
+import { LiteHashDRBG } from './LiteHashDRBG.js';
+import { RandUtil } from './RandUtil.js';
+
+export interface TournamentRngContext {
+    openYear: number;
+    openMonth: number;
+    stage: number;
+    phase: number;
+    matchIndex: number;
+    participantIndex: number;
+    gameIndex?: number;
+    extraSeed?: string | number;
+}
+
+const buildTournamentSeedKey = (baseSeed: string, context: TournamentRngContext): string => {
+    const gameIndex = context.gameIndex !== undefined ? `|game:${context.gameIndex}` : '';
+    const extraSeed = context.extraSeed !== undefined ? `|extra:${context.extraSeed}` : '';
+    return [
+        'Tournament',
+        `open:${context.openYear}-${context.openMonth}`,
+        `stage:${context.stage}`,
+        `phase:${context.phase}`,
+        `match:${context.matchIndex}`,
+        `participant:${context.participantIndex}`,
+        gameIndex,
+        extraSeed,
+        `seed:${baseSeed}`,
+    ]
+        .filter((value) => value.length > 0)
+        .join('|');
+};
+
+export const createTournamentRng = (baseSeed: string, context: TournamentRngContext): RandUtil =>
+    new RandUtil(LiteHashDRBG.build(buildTournamentSeedKey(baseSeed, context)));
+
+export const createTournamentSeedKey = (baseSeed: string, context: TournamentRngContext): string =>
+    buildTournamentSeedKey(baseSeed, context);
diff --git a/packages/infra/prisma/game.prisma b/packages/infra/prisma/game.prisma
index 6684958..8aa629a 100644
--- a/packages/infra/prisma/game.prisma
+++ b/packages/infra/prisma/game.prisma
@@ -220,6 +220,19 @@ model LogEntry {
     @@map("log_entry")
 }
 
+model ErrorLog {
+    id        Int      @id @default(autoincrement())
+    category  String
+    source    String?  @map("source")
+    message   String
+    trace     String?
+    context   Json     @default(dbgenerated("'{}'::jsonb"))
+    createdAt DateTime @default(now()) @map("created_at")
+
+    @@index([category, id])
+    @@map("error_log")
+}
+
 model InheritancePoint {
     id        Int      @id @default(autoincrement())
     userId    String   @map("user_id")
diff --git a/packages/infra/src/errorLogRepository.ts b/packages/infra/src/errorLogRepository.ts
new file mode 100644
index 0000000..e6847b7
--- /dev/null
+++ b/packages/infra/src/errorLogRepository.ts
@@ -0,0 +1,68 @@
+import type { GamePrisma, GamePrismaClient } from './gamePrisma.js';
+
+export interface ErrorLogQueryOptions {
+    limit?: number;
+    beforeId?: number;
+    category?: string;
+}
+
+export interface ErrorLogCreateInput {
+    category: string;
+    message: string;
+    source?: string;
+    trace?: string;
+    context?: GamePrisma.InputJsonValue;
+}
+
+export interface ErrorLogView {
+    id: number;
+    category: string;
+    source: string | null;
+    message: string;
+    trace: string | null;
+    context: GamePrisma.JsonValue;
+    createdAt: Date;
+}
+
+const buildPaginationWhere = (
+    base: GamePrisma.ErrorLogWhereInput,
+    options: ErrorLogQueryOptions
+): GamePrisma.ErrorLogWhereInput => {
+    if (options.beforeId) {
+        return {
+            ...base,
+            id: { lt: options.beforeId },
+        };
+    }
+    return base;
+};
+
+const buildFindArgs = (
+    where: GamePrisma.ErrorLogWhereInput,
+    options: ErrorLogQueryOptions
+): GamePrisma.ErrorLogFindManyArgs => ({
+    where: buildPaginationWhere(where, options),
+    orderBy: { id: 'desc' },
+    take: options.limit ?? 50,
+});
+
+export class ErrorLogRepository {
+    constructor(private readonly prisma: GamePrismaClient) {}
+
+    async createErrorLog(input: ErrorLogCreateInput): Promise<ErrorLogView> {
+        return this.prisma.errorLog.create({
+            data: {
+                category: input.category,
+                source: input.source ?? null,
+                message: input.message,
+                trace: input.trace ?? null,
+                context: input.context ?? {},
+            },
+        });
+    }
+
+    async listErrorLogs(options: ErrorLogQueryOptions = {}): Promise<ErrorLogView[]> {
+        const base: GamePrisma.ErrorLogWhereInput = options.category ? { category: options.category } : {};
+        return this.prisma.errorLog.findMany(buildFindArgs(base, options));
+    }
+}
diff --git a/packages/infra/src/index.ts b/packages/infra/src/index.ts
index 4e3738b..25bf645 100644
--- a/packages/infra/src/index.ts
+++ b/packages/infra/src/index.ts
@@ -10,6 +10,7 @@ export {
 } from './gatewayPrisma.js';
 export type { GatewayPrismaClient } from './gatewayPrisma.js';
 export * from './db.js';
+export * from './errorLogRepository.js';
 export * from './logRepository.js';
 export * from './redis.js';
 export * from './turnEngineDb.js';
diff --git a/packages/logic/src/index.ts b/packages/logic/src/index.ts
index 68b8a52..fcb6d06 100644
--- a/packages/logic/src/index.ts
+++ b/packages/logic/src/index.ts
@@ -15,5 +15,6 @@ export * from './ports/worldSnapshot.js';
 export * from './scenario/index.js';
 export * from './triggers/index.js';
 export * from './turn/index.js';
+export * from './tournament/index.js';
 export * from './world/index.js';
 export * from './war/index.js';
diff --git a/packages/logic/src/tournament/battle.ts b/packages/logic/src/tournament/battle.ts
new file mode 100644
index 0000000..94abd91
--- /dev/null
+++ b/packages/logic/src/tournament/battle.ts
@@ -0,0 +1,186 @@
+import { createTournamentRng } from '@sammo-ts/common';
+
+import {
+    TournamentType,
+    type TournamentBattleInput,
+    type TournamentBattleResult,
+    type TournamentBattleLogEntry,
+} from './types.js';
+
+const clampPositive = (value: number, fallback = 0): number => {
+    if (!Number.isFinite(value)) {
+        return fallback;
+    }
+    return value;
+};
+
+const round = (value: number): number => Math.round(value);
+
+const getLogRatio = (lvl1: number, lvl2: number): number => {
+    if (lvl1 >= lvl2) {
+        return 1 + Math.log10(1 + lvl1 - lvl2) / 10;
+    }
+    return 1 - Math.log10(1 + lvl2 - lvl1) / 10;
+};
+
+const resolveTournamentStat = (type: TournamentType, stats: { leadership: number; strength: number; intel: number }): number => {
+    switch (type) {
+        case TournamentType.LEADERSHIP:
+            return stats.leadership;
+        case TournamentType.STRENGTH:
+            return stats.strength;
+        case TournamentType.INTEL:
+            return stats.intel;
+        case TournamentType.TOTAL:
+        default:
+            return (stats.leadership + stats.strength + stats.intel) * (7 / 15);
+    }
+};
+
+export const resolveTournamentBattle = (input: TournamentBattleInput): TournamentBattleResult => {
+    const { attacker, defender, battleType, context } = input;
+    const attackerStat = resolveTournamentStat(input.type, attacker.stats);
+    const defenderStat = resolveTournamentStat(input.type, defender.stats);
+
+    const rng = createTournamentRng(input.baseSeed, {
+        openYear: context.openYear,
+        openMonth: context.openMonth,
+        stage: context.stage,
+        phase: context.phase,
+        matchIndex: context.matchIndex,
+        participantIndex: 0,
+        extraSeed: `${attacker.id}:${defender.id}`,
+    });
+
+    const energyBaseAttacker = round(attackerStat * getLogRatio(attacker.level, defender.level) * 10);
+    const energyBaseDefender = round(defenderStat * getLogRatio(attacker.level, defender.level) * 10);
+    let energyAttacker = energyBaseAttacker;
+    let energyDefender = energyBaseDefender;
+
+    const maxTurns = battleType === 0 ? 10 : 100;
+    const log: string[] = [];
+    const logEntries: TournamentBattleLogEntry[] = [];
+
+    log.push(`<S>●</> <Y>${attacker.name}</> <C>(${energyBaseAttacker})</> vs <C>(${energyBaseDefender})</> <Y>${defender.name}</>`);
+
+    let totalDamageAttacker = 0;
+    let totalDamageDefender = 0;
+    let selected = 2;
+
+    for (let phase = 1; phase <= maxTurns; phase += 1) {
+        const baseDamageAttacker = round(defenderStat * (rng.nextInt(21) + 90) / 130);
+        const baseDamageDefender = round(attackerStat * (rng.nextInt(21) + 90) / 130);
+        let damageAttacker = baseDamageAttacker;
+        let damageDefender = baseDamageDefender;
+
+        if (attackerStat >= rng.nextInt(100)) {
+            damageDefender += round(attackerStat * (rng.nextInt(41) + 10) / 130);
+        }
+        if (defenderStat >= rng.nextInt(100)) {
+            damageAttacker += round(defenderStat * (rng.nextInt(41) + 10) / 130);
+        }
+
+        let criticalAttacker = false;
+        let criticalDefender = false;
+        let factorAttacker = 1;
+        let factorDefender = 1;
+
+        if (energyBaseAttacker / 5 > energyAttacker && damageAttacker > damageDefender && attackerStat >= rng.nextInt(300)) {
+            factorDefender = round((rng.nextInt(301) + 200) / 100);
+            criticalAttacker = true;
+            log.push(`<S>●</> <Y>${attacker.name}</>의 분노의 일격!`);
+        }
+        if (energyBaseDefender / 5 > energyDefender && damageDefender > damageAttacker && defenderStat >= rng.nextInt(300)) {
+            factorAttacker = round((rng.nextInt(301) + 200) / 100);
+            criticalDefender = true;
+            log.push(`<S>●</> <Y>${defender.name}</>의 분노의 일격!`);
+        }
+
+        damageAttacker = round(damageAttacker * factorAttacker);
+        damageDefender = round(damageDefender * factorDefender);
+
+        if (phase === 1) {
+            if (attackerStat * 0.9 > defenderStat && attackerStat >= rng.nextInt(400)) {
+                damageDefender += round(attackerStat * (rng.nextInt(31) + 70) / 100);
+            }
+            if (defenderStat * 0.9 > attackerStat && defenderStat >= rng.nextInt(400)) {
+                damageAttacker += round(defenderStat * (rng.nextInt(31) + 70) / 100);
+            }
+        } else {
+            if (!criticalAttacker && attackerStat >= rng.nextInt(1000)) {
+                damageDefender += round(attackerStat * (rng.nextInt(31) + 20) / 100);
+            }
+            if (!criticalDefender && defenderStat >= rng.nextInt(1000)) {
+                damageAttacker += round(defenderStat * (rng.nextInt(31) + 20) / 100);
+            }
+        }
+
+        damageAttacker = clampPositive(round(damageAttacker), 0);
+        damageDefender = clampPositive(round(damageDefender), 0);
+
+        energyAttacker -= damageAttacker;
+        energyDefender -= damageDefender;
+
+        totalDamageAttacker += damageAttacker;
+        totalDamageDefender += damageDefender;
+
+        const entryText =
+            `<S>●</> ${String(phase).padStart(2, '0')}合 : ` +
+            `<C>${String(round(energyAttacker)).padStart(3, '0')}</>` +
+            `<span class="ev_highlight">(-${String(round(damageAttacker)).padStart(3, '0')})</span>` +
+            ' vs ' +
+            `<span class="ev_highlight">(-${String(round(damageDefender)).padStart(3, '0')})</span>` +
+            `<C>${String(round(energyDefender)).padStart(3, '0')}</>`;
+
+        log.push(entryText);
+        logEntries.push({
+            phase,
+            attackerEnergy: round(energyAttacker),
+            defenderEnergy: round(energyDefender),
+            attackerDamage: damageAttacker,
+            defenderDamage: damageDefender,
+            text: entryText,
+        });
+
+        if (energyAttacker <= 0 && energyDefender <= 0) {
+            if (battleType === 0) {
+                selected = 2;
+                break;
+            }
+            selected = energyAttacker > energyDefender ? 0 : 1;
+            break;
+        }
+        if (energyAttacker <= 0) {
+            selected = 1;
+            break;
+        }
+        if (energyDefender <= 0) {
+            selected = 0;
+            break;
+        }
+    }
+
+    if (selected === 0) {
+        log.push(`<S>●</> <Y>${attacker.name}</> <S>승리</>!`);
+    } else if (selected === 1) {
+        log.push(`<S>●</> <Y>${defender.name}</> <S>승리</>!`);
+    } else {
+        log.push(`<S>●</> <Y>${attacker.name}</> <S>무승부</>!`);
+    }
+
+    const winnerId = selected === 0 ? attacker.id : selected === 1 ? defender.id : null;
+    const loserId = selected === 0 ? defender.id : selected === 1 ? attacker.id : null;
+
+    return {
+        winnerId,
+        loserId,
+        draw: selected === 2,
+        rounds: logEntries.length,
+        totalDamage: {
+            attacker: totalDamageAttacker,
+            defender: totalDamageDefender,
+        },
+        log,
+        logEntries,
+    };
+};
diff --git a/packages/logic/src/tournament/index.ts b/packages/logic/src/tournament/index.ts
new file mode 100644
index 0000000..cc70a9d
--- /dev/null
+++ b/packages/logic/src/tournament/index.ts
@@ -0,0 +1,2 @@
+export * from './types.js';
+export * from './battle.js';
diff --git a/packages/logic/src/tournament/types.ts b/packages/logic/src/tournament/types.ts
new file mode 100644
index 0000000..cd032ce
--- /dev/null
+++ b/packages/logic/src/tournament/types.ts
@@ -0,0 +1,60 @@
+export const TournamentType = {
+    TOTAL: 0,
+    LEADERSHIP: 1,
+    STRENGTH: 2,
+    INTEL: 3,
+} as const;
+
+export type TournamentType = (typeof TournamentType)[keyof typeof TournamentType];
+
+export interface TournamentStats {
+    leadership: number;
+    strength: number;
+    intel: number;
+}
+
+export interface TournamentParticipant {
+    id: number;
+    name: string;
+    stats: TournamentStats;
+    level: number;
+}
+
+export interface TournamentBattleLogEntry {
+    phase: number;
+    attackerEnergy: number;
+    defenderEnergy: number;
+    attackerDamage: number;
+    defenderDamage: number;
+    text: string;
+}
+
+export interface TournamentBattleResult {
+    winnerId: number | null;
+    loserId: number | null;
+    draw: boolean;
+    rounds: number;
+    totalDamage: {
+        attacker: number;
+        defender: number;
+    };
+    log: string[];
+    logEntries: TournamentBattleLogEntry[];
+}
+
+export interface TournamentBattleContext {
+    openYear: number;
+    openMonth: number;
+    stage: number;
+    phase: number;
+    matchIndex: number;
+}
+
+export interface TournamentBattleInput {
+    type: TournamentType;
+    battleType: 0 | 1; // 0: 승무패, 1: 승패
+    attacker: TournamentParticipant;
+    defender: TournamentParticipant;
+    context: TournamentBattleContext;
+    baseSeed: string;
+}