---
title: "Combat Rules: API"
package: "@phaser-ae/combat-rules"
tier: Pro
version: 3.0.0-3
released: 2026-10-14
updated: 2026-10-20
description: "The numbers behind a fight: damage, healing, armour, elemental resistance, shields and timed status effects, resolved in a fixed order with an event for everything that happened."
url: https://phaser.io/packs/combat-rules/api
site: Phaser - https://phaser.io
---

# Combat Rules: API

`@phaser-ae/combat-rules` — Damage, healing, armour, elemental resistance, shields and timed status effects with ordered events.

## The pack

### `combatRules`

```ts
function combatRules():Pack<{combatRules:typeof rules}>
```

Install renderer-independent combat rules policies.

## Helpers

### `combatant`

```ts
function combatant(id: string, team: string, maxHp = 100, options: Partial<Omit<Combatant, 'id' | 'team' | 'maxHp'>> = {}): Combatant
```

Construct a combatant with independent status and resistance storage.

### `createCombat`

```ts
function createCombat(entities: readonly Combatant[], seed = 0)
```

Create a reusable combat resolver.

### `createCombatDuel`

```ts
function createCombatDuel(seed: number, difficulty: Difficulty = 'medium')
```

Every generated turn challenge includes a verified winning action sequence.

### `solveCombatDuel`

```ts
function solveCombatDuel(initial: CombatDuel, maxTurns = 28): DuelMove[] | null
```

Search a bounded beam of actual combat states; returns a winning sequence or null, never labels a timeout unsolvable.

## Classes

### `Combat`

```ts
class Combat
```

Renderer-independent, ordered effect resolution. Armour is flat, resistance fractional; shields absorb last.

- `readonly entities: Combatant[]` — Every combatant, in the order given (copies of those passed in); their hit points, shields and statuses change as effects land.
- `readonly events: CombatEvent[]` — Events not yet taken by `drain`, oldest first.
- `time: number` — Elapsed combat time in seconds, advanced by `tick`.
- `turn: number` — The turn counter, advanced by `nextTurn`; starts at 0.
- `constructor(entities: readonly Combatant[], seed = 0)`
- `get(id: string): Combatant` — The combatant with this id. Throws if there is none.
- `apply(source: string, target: string, effects: readonly Effect[]): CombatEvent[]` — Validate the entire sequence before applying it; dead targets reject damage, healing and status.
- `hasTag(id: string, tag: string): boolean` — Whether any status on the combatant has this tag. Throws if the id is unknown.
- `tick(seconds: number)` — Advances combat time by `seconds`, running periodic damage and healing at every boundary and expiring `seconds`-clock statuses. Throws if `seconds` is negative or not finite.
- `nextTurn()` — Ends the turn: adds one to `turn` and advances the `turns`-clock statuses by one, so periodic effects tick and durations fall.
- `drain(): CombatEvent[]` — Takes every pending event, oldest first, and clears them.
- `snapshot(): CombatSnapshot` — The whole combat as plain JSON, to save, with the critical-hit stream's state.
- `static restore(s: CombatSnapshot): Combat` — Rebuilds a combat from `snapshot()`, continuing the same critical-hit stream. Throws if the snapshot's version is not 2 or its contents are invalid.

### `CombatDuel`

```ts
class CombatDuel
```

Small seeded turn challenge demonstrating numerical policies, rather than owning any presentation.

- `readonly combat: Combat` — The combat being played, with the combatants `hero` and `enemy`.
- `readonly enemyMoves: { name: string; effects: Effect[]; }[]` — The enemy's moves, played in rotation: each a name and the effects it applies to the hero.
- `turn: number` — Turns taken so far.
- `energy: number` — Energy the hero has to spend, 0 to 6; starts at 5.
- `won: boolean` — Whether the enemy has been defeated.
- `lost: boolean` — Whether the hero has been defeated.
- `solution: DuelMove[]` — A verified winning sequence of moves, filled in by `createCombatDuel`; empty on a duel built directly.
- `message: string` — A line describing the last result, for the host to show.
- `constructor(readonly seed: number, readonly difficulty: Difficulty = 'medium')`
- `get intent()` — The enemy's next move, applied to the hero right after the hero's next move.
- `play(move: DuelMove)` — Plays a move and then the enemy's reply, and returns true. Returns false instead if the duel is over or the hero lacks the energy for the move.

## Types

### `Combatant`

```ts
interface Combatant
```

Something that can fight: hit points, shield, armour, element resistances and the statuses on it. Build one with `combatant`.

- `id: string` — Unique name used to address it in `Combat` calls; not empty.
- `team: string` — The side it fights for. The rules store it for the host to group and target by and never read it; not empty.
- `hp: number` — Current hit points, from 0 to `maxHp`; at 0 it is defeated and rejects further damage, healing and statuses.
- `maxHp: number` — Hit points at full health; at least 1.
- `shield: number` — Damage points that absorb a hit, after armour and resistance, before hit points are lost; 0 or more.
- `armour: number` — Flat damage taken off every hit before resistance, unless the hit ignores armour; 0 or more.
- `resistances: Record<string, number>` — Per element, the fraction of that element's damage resisted, from -1 (takes double) to 1 (immune). An element with no entry is not resisted; an effect with no element is `physical`.
- `statuses: Status[]` — The statuses on it now; each id appears once.

### `CombatEvent`

```ts
interface CombatEvent
```

One thing that happened to a combatant, in the order it happened. `Combat.apply` returns them and `drain` takes them.

- `sequence: number` — Running number from 1, unique within the combat.
- `time: number` — Combat time in seconds when it happened.
- `turn: number` — The turn counter when it happened.
- `source: string` — Id of the combatant that caused it.
- `target: string` — Id of the combatant it happened to.
- `kind: string` — What happened: `damage`, `absorbed`, `defeated`, `heal`, `shield`, `status`, `cleansed`, `expired` or `rejected`.
- `amount: number` — Its size: hit points for damage, absorbed, heal and shield; stacks for status, cleansed and expired; 0 for defeated and rejected.
- `detail: string` — Extra detail: the element or `critical` for damage, the status id for status, cleansed and expired, `target dead` for rejected.

### `CombatSnapshot`

```ts
interface CombatSnapshot
```

A combat saved as plain JSON, to restore with `Combat.restore`.

- `version: 2` — 2 since the critical-hit stream became the kernel's generator; a version 1 snapshot is refused.
- `time: number` — Combat time in seconds.
- `turn: number` — The turn counter.
- `random: RngState` — Where the critical-hit stream stands: the four words of the kernel's `rng.snapshot()`.
- `sequence: number` — The number of events recorded so far.
- `entities: Combatant[]` — Every combatant in the combat, with its current state.

### `DuelMove`

```ts
type DuelMove = 'strike' | 'fire' | 'guard' | 'heal' | 'cleanse'
```

A move the hero can make: `strike` (18 damage, may crit, restores 1 energy), `fire` (25 fire damage that ignores armour, costs 2), `guard` (24 shield, restores 1), `heal` (32 hit points, costs 3) or `cleanse` (removes statuses, costs 1).

### `Effect`

```ts
type Effect = { kind: 'damage'; amount: number; element?: string; critChance?: number; critMultiplier?: number; ignoreArmour?: boolean; } | { kind: 'heal' | 'shield'; amount: number; } | { kind: 'status'; status: StatusSpec; } | { kind: 'cleanse'; statusId?: string; }
```

One thing that can be done to a target, applied in order by `Combat.apply`.
- `damage`: `amount` hit points before armour and resistance; `element` default `physical`; `critChance` (0 to 1, default 0) is the chance of a critical hit, which multiplies the damage by `critMultiplier` (default 1.5, at least 1); `ignoreArmour` skips flat armour.
- `heal`: restores `amount` hit points, up to `maxHp`.
- `shield`: adds `amount` shield points.
- `status`: applies a status.
- `cleanse`: removes the status named by `statusId`, or every status when it is omitted.

### `Status`

```ts
interface Status
```

A timed condition on a combatant that can deal or heal a set amount every `interval`: poison, regeneration, a marked target. Stacks multiply its per-tick amounts.

- `id: string` — Names the status; applying one with an id already present stacks, refreshes or replaces it according to `policy`.
- `remaining: number` — Time left before it expires, on its own `clock`: seconds or turns. Above 0.
- `clock: 'seconds' | 'turns'` — What counts down `remaining`: `seconds` follow `tick`, `turns` follow `nextTurn`. A status keeps its clock unless it is replaced.
- `stacks: number` — Current stacks, from 1 to `maxStacks`; the per-tick damage and healing are multiplied by it.
- `maxStacks: number` — Most stacks it can hold, a whole number from 1 to 1000.
- `policy: 'refresh' | 'replace' | 'stack'` — What reapplying it does: `refresh` keeps the longer remaining time, `stack` does the same and adds stacks up to `maxStacks`, `replace` swaps the old one for the new.
- `interval: number` — Clock units (seconds or turns) between periodic ticks of its damage and healing. Above 0.
- `elapsed: number` — Clock units since its last tick; 0 on a new status.
- `damage: number` — Damage dealt to the holder on each tick, per stack. It ignores armour. 0 for none.
- `healing: number` — Hit points healed on each tick, per stack. 0 for none.
- `element: string` — The element of its tick damage, matched against the holder's `resistances`.
- `tags: string[]` — Labels on the status; `Combat.hasTag` tests a combatant for them, so the host can ask whether it is burning.

### `StatusSpec`

```ts
type StatusSpec = Omit<Status, 'elapsed' | 'stacks'> & { stacks?: number; }
```

A status as authored in an `Effect`: a `Status` without the running `elapsed`, and with `stacks` optional (default 1).

---

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