To defeat HALT, you must do the following:

1. Get marked by the marking helper via reversaldef/hitdef, your character's main body must be marked.
2. Set your alive value to something other than 1.
3. Don't use any projectiles to damage the armor helper
4. Self-inflict exactly 2147483647 damage upon yourself.

Doing all of these will slowly drain HALT's power bar, will die when it hits 0.