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 (a horizontal invisible border separating the surface from the underground), one or more Dungeon Guardians quickly fly at the player, dealing 1000 / damage each, which effectively kills most players instantly. Dungeon Guardians are large, very fast, and travel through all blocks.

Any player who attacks a Dungeon Guardian,   regardless of the weapon or other equipment ( with the exception of frostburn items), will deal only 1 damage, or 2 for critical hits. This means that the Dungeon Guardian will   always/ usually take an average of 1.04 damage.

Tips

 * Because of the extreme effort that must be done to defeat a Dungeon Guardian, and also because its only drop, the Bone Key, isn't very useful, there isn't much point in defeating a Dungeon Guardian unless one wants bragging rights.
 * However, on the, the bone key is required for the "Pet Hoarder" achievement.
 * Killing a Dungeon Guardian is possible, though it would take thousands of hits due to its absurdly high defense (The Phantasm Bow and Luminite Arrows are recommended, because of the buildup that can easily drain his health by hundreds a second). Combined with the fact that you generally need to contend with multiple Guardians at once, victory is extremely unlikely unless you prepare carefully for the encounter.
 * High speed and critical chance are crucial for fighting the Dungeon Guardian, as every hit will do 1 damage, and every critical hit will do 2 damage.
 * Dungeon Guardians will adhere to the same spawn limits as any other enemy: if there are too many monsters on-screen at once, they will not spawn. Using the Duck Statue glitch and filling up all spawn slots will stop them from spawning, even below 0'.
 * A good tactic is to acquire full Titanium armor, allowing you to occasionally dodge otherwise lethal hits.
 * The player can outrun the Dungeon Guardian with the Unicorn Mount. The Unicorn Mount's speed reaches 61 mph, faster than the Dungeon Guardian, so the player will only need to stop to allow the Dungeon Guardian to catch up.
 * Use of a Life Drain is particularly effective against the Dungeon Guardian, as the Life Drain can deal 5 damage a tick.
 * Another good way to kill the Dungeon Guardian is to lure it into a circle of ropes, keep going around the ropes. Then, throw a boomerang in the middle. The Dungeon Guardian will stay in the middle while taking damage from the boomerang.
 * However, the Guardian's speed will almost always overtake the player. This strategy is best done with a circular HOIK.
 * In the the Chlorophyte Shotbow or Tsunami combined with Heart Arrow while wearing full Frost Armor (as the Dungeon Guardian is not immune to Frostburn debuff) can be a good way to defeat the Dungeon Guardian.
 * One of the most general strategies is to dig a hole straight down through the dungeon, use a pair of wings with increased vertical speed (Fishron, Stardust, Solar) and Cosmic Car Key. Go down through the hole, and when the Guardian appears, quickly fly up through the hole and mount. From there you can damage it however you want, without ever being touched.
 * In Expert mode, Dungeon Guardians will have double the health and deal double the damage. Due to this, it is recommended to try and defeat the Dungeon Guardian on a normal world to save time, money (All enemies take money from the ground) and further troubles.
 * On the the Dungeon Guardian can be killed very easily with Fishron Wings, Frost Armor, and any Ranged weapon. This is because Frostburn will do 32 damage every time the damage ticks. This can kill it in as few as 20 shots.
 * On the, using the Cosmic Car Key is a good tactic, as you can fly across the whole world without ever being touched until you reach the edge. There, you can loop back the other direction.
 * Any Gun, an Endless Musket Pouch, and a Cosmic Car Key can get the job done. A Rod of Discord would be helpful if you happen to have one lying around.
 * On, if somehow you can get close to the Dungeon Guardian without getting hit, then a Tizona can be a great choice, with Frost armor of course. The Bleeding and Frostburn debuffs will stack and do 66 damage per tick, killing the Dungeon Guardian in seconds.
 * Crystal Bullets may be a good choice for bullets when using a gun since they shatter on impact into 3 shards, which also deal damage to the Dungeon Guardian. Pairing this with Frostburn, high Critical Strike, and a very fast gun (e.g. Chain Gun, S.D.M.G, Megashark) can be a very effective strategy to kill it quickly.

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.
 * Despite being initially intended to be unbeatable, it is not invulnerable like Spike Balls, Blazing Wheels, and True Eyes of Cthulhu are.
 * It has no corpse on the, but on the , the remains of Skeletron's hands will appear upon its death.
 * Its head spins clockwise when the player is going left and counterclockwise when going right.