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.

Strategy

 * If there are at least two players, they can build a house and set their spawnpoint there. One player runs around the dungeon guardian, keeping him occupied, and the other player runs at the dungeon guardian in turtle armor.  This will kill the dungeon guardian if the kamikaze player can touch the dungeon guardian twice, which often isn't a problem as long as the other player can dodge effectively.  This also works in singleplayer, if the player has a Black Belt or Master Ninja Gear they have a small chance to live after reflecting the dungeon guardian's attack.  When the dungeon guardian attacks the player again, it will die.  This may take multiple attempts, as the dodge chance is quite low.

(This may not work after the change to the Guardian's damage since it will no longer do 9000 damage to itself, only 1000)