Crabkingbrain

Based on game build 714014 | Last updated: 2026-02-27

Overview

This brain component implements the artificial intelligence for the Crab King boss entity in Don't Starve Together. It uses a Behavior Tree (BT) architecture to determine high-priority actions such as casting freezing projectiles, summoning ice claws, and seeking to heal when damaged. The behavior tree is rooted in an IfNode that evaluates whether the Crab King is not currently performing inert, casting, fixing, or spawning states. Within the doing branch, priority-based DoAction nodes evaluate helper functions (ShouldHeal, ShouldFreeze, ShouldHaveClaws) to trigger corresponding actions only when their specific conditions are met.

Dependencies & Tags

• Components used:

  • combat: accessed via inst.components.combat.target to check active targets.
  • freezable: accessed via inst.components.freezable:IsFrozen() to verify entity freeze state.
  • health: accessed via inst.components.health:GetPercent() to determine healing threshold.
  • knownlocations: used to remember the spawn point on initialization.
  • timer: accessed via inst.components.timer:TimerExists(name) to check for active timers (e.g., "taunt", "cannon_timer").

• Tags:

  • icewall: checked to modify behavior (e.g., enables healing, disables some summoning/casting).
  • boat, character, animal, monster, smallcreature: used for entity filtering during targeting logic.

Properties

Property	Type	Default Value	Description
wantstosummonclaws	boolean?	nil	Set to true if claws should be summoned; cleared otherwise.
wantstoheal	boolean?	nil	Set to true if healing is triggered; cleared otherwise.
wantstotaunt	boolean?	nil	Set to true if taunt timer is active; cleared otherwise.
wantstofreeze	boolean?	nil	Set to true when freezing is possible (no ice wall, cooldowns clear, valid targets near).
wantstocannon	boolean?	nil	Set to true when cannon attack is possible (no "icewall" tag, no "cannon_timer", valid targets).
damagetotal	number?	nil	Cumulative damage value used to determine stage transitions and freeze eligibility.

Main Functions

OnStart()

• Description: Initializes the behavior tree for the Crab King. Constructs a priority-based node tree that first checks if the entity is not in an inert, casting, fixing, or spawning state. Within that condition, it evaluates three DoAction nodes in order: ShouldHeal, ShouldFreeze, and ShouldHaveClaws. The first one returning true executes its associated behavior.
• Parameters: None.
• Returns: nil.

OnInitializationComplete()

• Description: Records the Crab King's initial spawn position using the knownlocations component under the key "spawnpoint".
• Parameters: None.
• Returns: nil.

Helper Functions (used in Behavior Tree)

ShouldHaveClaws(inst)

• Description: Sets inst.wantstosummonclaws = true if the Crab King should summon ice claws. This occurs only when it lacks the "icewall" tag, has no arms (inst.arms is falsy), is not in a "taunt" timer state, and is not currently casting.
• Parameters:
  • inst (Entity): The Crab King entity.
• Returns: nil.

ShouldHeal(inst)

• Description: Sets inst.wantstoheal = true if the Crab King’s health is below full (health:GetPercent() < 1), it has the "icewall" tag, and is not currently taunting. Otherwise, clears wantstoheal.
• Parameters:
  • inst (Entity): The Crab King entity.
• Returns: nil.

ShouldTaunt(inst)

• Description: Sets inst.wantstotaunt = true if a "taunt" timer exists, otherwise clears it.
• Parameters:
  • inst (Entity): The Crab King entity.
• Returns: nil.

ShouldFreeze(inst)

• Description: Evaluates whether the Crab King can execute a freeze attack. Triggers only when:

  • Not having the "icewall" tag,
  • Cumulative damage damagetotal <= TUNING.CRABKING_FREEZE_THRESHOLD,
  • Health is at or below stage 1 threshold (health:GetPercent() <= TUNING.CRABKING_STAGE1_THRESHOLD).

  Then checks if a "boat_ice" entity is present within a 25-unit radius, or if valid combat targets (character/animal/monster/smallcreature) exist within 20 units and are either characters or non-character entities with "combat" component targeting the Crab King. If either condition is satisfied, inst.wantstofreeze is set to true.

• Parameters:

  • inst (Entity): The Crab King entity.

• Returns: nil.

ShouldCannon(inst)

• Description: Evaluates whether the Crab King can perform a cannon attack. Triggers when:

  • No active "cannon_timer" is running,
  • Not having the "icewall" tag.

  It searches for "boat_ice" within 25 units and potential targets within 20 units. Target filtering removes any entity that is:

  • Not a character and does not have "combat" targeting the Crab King, or
  • Lacks a freezable component, or
  • Is currently frozen (freezable:IsFrozen()).

  If valid entities (boats or targets) are found, inst.wantstocannon is set to true.

• Parameters:

  • inst (Entity): The Crab King entity.

• Returns: nil.

Events & Listeners

None identified.