> For the complete documentation index, see [llms.txt](https://series-1.gitbook.io/rundot-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://series-1.gitbook.io/rundot-docs/v5.27.0/readme/syncplay/syncplay-gameplay-effects.md).

# Syncplay: Gameplay Effects

> **STABLE:** This module API passed independent FPS damage and ARPG ability/status/damage consumers at the two-genre promotion gate.

Import the code-only module from:

```ts
import {
  applySyncplayGameplayEffectCommands,
  createSyncplayGameplayEffectsSlice,
  gameplayEffectsComponent,
  stepSyncplayGameplayEffects,
} from '@series-inc/rundot-syncplay/modules/gameplay-effects'
```

Definitions contain ordered typed damage, healing, resource, status, or ability interrupt operations with exact integer amount formulas. Immediate effects emit on application. Periodic effects use canonical duration, tick interval, tick ordinal, and `add`, `refresh`, or `replace` duplicate semantics.

The composition helper prevalidates the complete command roster and target map, then applies combat and stats/abilities changes atomically in target and command ID order. A missing target or rejected nested operation leaves every caller slice unchanged. Every target explicitly declares `statsFrame: 'advance'` when the compositor owns that frame's stats timer step, or `statsFrame: 'already-advanced'` when the game already stepped abilities and statuses. This prevents accidental double advancement while keeping the target contract fail-closed.

Target selection, aim, crits, random failure, encounter balance, presentation, and item-consumption policy remain caller-owned. Malformed state, definitions, commands, or target maps fail closed with stable `SYNCPLAY_GAMEPLAY_EFFECTS_*` errors.