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Tentacle Arm

Based on game build 714014 | Last updated: 2026-03-07

Overview​

tentacle_arm represents a mobile boss combat entity (tentacle arm) that engages enemies within range, retracts when players move away, and is removed upon full retreat if sleeping. It integrates health, combat, proximity sensing, and sanity modulation, and interacts with the acidinfusible system for damage tuning. It is primarily used in tentacle pillar encounters in the Caves.

Usage example​

local inst = Prefab("tentacle_pillar_arm", fn, assets, prefabs)()
inst.components.combat:SetTarget(target)
inst:Emerge() -- causes emergence animation and starts combat engagement
inst:Retract() -- retracts the arm and stops attacking

Dependencies & tags​

Components used: health, combat, playerprox, sanityaura, inspectable, acidinfusible, hauntable
Tags added: monster, hostile, tentacle_pillar_arm, wet, soulless, NPCcanaggro
Tags checked: _combat, _health, character, monster, animal, tentacle_pillar, prey, INLIMBO

Properties​

PropertyTypeDefault ValueDescription
retractedbooleantrueWhether the arm is currently retracted.
retreatbooleanfalseSet when full_retreat event fires; triggers removal upon sleeping.
sleeptasktasknilDelayed removal task created when waking from sleep while in retreat state.
scrapbook_animstring"atk_idle"Animation name used for scrapbook entry.
scrapbook_removedepstable{"monstermeat"}List of prefabs whose removal does not affect this entity's scrapbook.

Main functions​

Emerge(inst)​

  • Description: Sets retracted to false and fires the "emerge" event if currently retracted. Used to awaken the arm for combat when players approach.
  • Parameters: inst (Entity) — the tentacle arm entity.
  • Returns: Nothing.
  • Error states: No effect if already emerged (retracted == false).

Retract(inst)​

  • Description: Sets retracted to true and fires the "retract" event if currently emerged. Used to return the arm to a dormant state when players are far.
  • Parameters: inst (Entity) — the tentacle arm entity.
  • Returns: Nothing.
  • Error states: No effect if already retracted (retracted == true).

OnFullRetreat(inst)​

  • Description: Handles full retreat logic: sets retreat = true or removes the entity immediately if sleeping.
  • Parameters: inst (Entity).
  • Returns: Nothing.

OnEntitySleep(inst)​

  • Description: If retreat is true and no sleep task is pending, schedules entity removal after 1 second.
  • Parameters: inst (Entity).
  • Returns: Nothing.

OnEntityWake(inst)​

  • Description: Cancels pending removal task if the entity wakes up.
  • Parameters: inst (Entity).
  • Returns: Nothing.

ShouldKeepTarget(inst, target)​

  • Description: Predicate used by combat to decide whether to maintain target engagement. Returns true only if target is valid, alive, near enough, and has health component.
  • Parameters:
    inst (Entity) — tentacle arm;
    target (Entity?) — proposed target.
  • Returns: boolean — true if combat should continue with target.

OnHit(inst, attacker, damage)​

  • Description: Called after dealing damage. If the attacker is a non-player follower and randomly succeeds, the attacker is ordered to stop attacking, and if the tentacle arm is already dead, it takes additional penalty damage.
  • Parameters:
    inst (Entity) — tentacle arm;
    attacker (Entity) — entity that dealt damage;
    damage (number) — damage dealt.
  • Returns: Nothing.

CustomOnHaunt(inst, haunter)​

  • Description: Custom hauntable reaction. With HAUNT_CHANCE_HALF chance, kills the arm if not already dead.
  • Parameters:
    inst (Entity);
    haunter (Entity) — the haunter.
  • Returns: boolean — true if haunt effect was applied.

Events & listeners​

  • Listens to: full_retreat — triggers full retreat behavior (see OnFullRetreat).
  • Pushes: emerge, retract — fired when arm state changes.
  • Uses: OnEntitySleep, OnEntityWake — instance methods for sleep/wake lifecycle events.