Fighter AI

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Fighter AI is an AI type used by a variety of enemies. Some Fighter AI enemies are able to open doors and Tall Gates(Desktop, Console and Mobile versions).


An NPC with the Fighter AI exhibits the following behavior:

  • Directly chases the player.
  • Jumps when necessary or if player is above them enough.
  • Navigates through platforms.

Opening doors and Tall Gates

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Some fighters are capable of opening doors and Tall Gates that are in their way to reach the player. When in front of one, they "hit" it () every second and open it after a certain number of hits.

Most fighters can open doors and Tall Gates at any time, while others can only do so during a Blood Moon. They are listed below.[1]

Only during a Blood Moon

When the player is in a Graveyard(Desktop, Console and Mobile versions), these enemies have a 1/60 (1.67%) chance to open a door/Tall Gate upon hitting it even outside of a Blood Moon. In For the worthy(Desktop, Console and Mobile versions) worlds, these enemies can never open doors/Tall Gates, not even during a Blood Moon.

Number of hits

Generally, fighters will open a door on the second hit (i.e. after 2 seconds) and a Tall Gate on the fifth hit (i.e. after 5 seconds). However, there are a few exceptions:[2]

  • ButcherButchers(Desktop, Console and Mobile versions) will open doors and Tall Gates on the first hit (i.e. after 1 second).
  • Angry BonesAngry BonesAngry Bones (all variants) will open doors on the first hit (i.e. after 1 second) and Tall Gates on the second hit (i.e. after 2 seconds).
  • Goblin ThiefGoblin Thieves will open Tall Gates on the fourth hit (i.e. after 4 seconds).

The number of hits is reset if the enemy walks away from the door/Tall Gate before opening it. For example, if a fighter hits a Tall Gate three times and then walks away, it will need to hit it five times anew in order to open it.


  • The Goblin Peon is unique in that it always destroys doors (but not Tall Gates) instead of opening them.
  • Doors can only be opened in the direction the enemy is facing. If the other side is obstructed, e.g. by a block or background object like a Work Bench, then they cannot be opened. Goblin Peons can still destroy doors in this case, however.


  • A level piece of land is ideal for battling fighters. A fast attacking or heavy knockback-inducing weapon is recommended. A magic weapon which can pierce through enemies multiple times (or indefinitely) is most effective when the player has all fighters lined up.
  • As Fighter AI enemies always try to maintain the same height as their target, creating a large pit with a bridge of platforms (and then standing lower than this bridge) will cause Fighter AI enemies to fall right through it.
  • Many Fighter AI enemies are exceptionally vulnerable to the Confused debuff, making them walk away from the player.

List of NPCs with Fighter AI



  1. Information taken from the Desktop version Desktop source code, method AI_003_Fighters() in Terraria.NPC.cs.
  2. Information taken from the Desktop version Desktop source code, method AI_003_Fighters() in Terraria.NPC.cs.