Dungeon Guardian

Dungeon Guardians are enemies that guard the Dungeon against intruders. If a player enters the Dungeon without first killing Skeletron and travels below zero depth (the horizontal midline of the map), multiple Dungeon Guardians quickly fly at the player, dealing 1,000 damage each, effectively killing any player instantly. Dungeon Guardians are large, very fast, and travel through blocks.

Dungeon Guardians are immune to the Poisoned, On Fire!, and Cursed Inferno debuffs.

Trivia

 * Originally, actual Skeletron Heads were used to guard the Dungeon. Killing all Skeletron Heads would count as defeating Skeletron, so the Dungeon Guardian was created to repair this unintentional behavior.

Bugs

 * If you teleport out with a Magic Mirror at the exact moment that a the Dungeon Guardian hits you, a death message will be displayed but you will survive. This can be used with Turtle armor to kill the dungeon guardian as it will still take the thorns damage and it will die the next time it hits you.
 * Sometimes 3 Dungeon Guardians will spawn at the same time.