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Main article: Bosses

The term "mechanical bosses" refers to three Hardmode bosses; The Destroyer, The Twins, and Skeletron Prime, which are grouped together under this generic term due to sharing certain characteristics: They can be summoned by "mechanical" items, and are themselves metallic and robotic in appearance, resembling mechanical versions of the pre-Hardmode bosses Eater of Worlds, Skeletron, and Eye of Cthulhu. In addition, there is a 10% chance that one will randomly spawn each night after the first Demon/Crimson Altar is destroyed in a world, and each will continue to spawn randomly until it is defeated at least once.

The mechanical bosses' summoning items can be crafted at a Hardmode Anvil. They also drop from all Hardmode enemies (except statue-spawned enemies and Meteor Heads) with a 1/2500 chance until their respective boss is defeated.

Defeating any single mechanical boss for the first time causes the following to happen:

Defeating all three mechanical bosses causes the following to happen:

Boss Spawn message Summoning item Dropped Soul type
The Destroyer The Destroyer "You feel vibrations from deep below..."
"You feel a quaking from deep underground..."
Mechanical Worm Mechanical Worm Soul of MightSoul of Might
The Twins The Twins "This is going to be a terrible night..." Mechanical Eye Mechanical Eye Soul of SightSoul of Sight
Skeletron Prime Skeletron Prime "The air is getting colder around you..."
"You feel the air getting colder around you..."
Mechanical Skull Mechanical Skull Soul of FrightSoul of Fright

Crafting

Summoning Items Recipes

ResultIngredientsCrafting station
Mechanical EyeMechanical Eye
Mythril AnvilMythril Anvil
or
Orichalcum AnvilOrichalcum Anvil
Mechanical SkullMechanical Skull
Mechanical WormMechanical Worm

Notes

  • It is possible to summon a mechanical boss pre-Hardmode if the summoning items are brought in from another world. However, if the Wall of Flesh has not been defeated, Plantera's Bulbs will not start spawning.
  • Once one of the spawning messages appears at random, fleeing to the underground, or logging out and back in again, can prevent the mechanical boss from spawning.

Tips

Trivia

  • All of the mechanical bosses seem to shoot a red death laser when in at least one of their forms.
  • They are the only bosses whose Expert-exclusive items are crafting materials.
  • Official Terraria Lore – According to the official game lore, the mechanical bosses are likely the parts of Cthulhu which the Mechanic was forced to build. This explains the lack of a mechanical counterpart of the Brain of Cthulhu, as the mechanical Cthulhu lacks a brain and the Mechanic was never able to finish it.
  • It seems that all mechanical bosses are made of hallowed bars since they drop them once destroyed.
  • Hallowed Bars, dropped by the mechanical bosses, are the one of the only bars that don't have a corresponding ore, the others being Spectre Bars and Shroomite Bars.

Achievements

Achievement Buckets of Bolts
Buckets of Bolts • Defeat the three nocturnal mechanical menaces: the Twins, the Destroyer, and Skeletron Prime.
Defeat all three Mechanical Bosses.
Category: Slayer Slayer
Achievement Mecha Mayhem
Mecha Mayhem • Do battle against the Twins, the Destroyer, and Skeletron Prime simultaneously and emerge victorious.
Defeat all three Mechanical Bosses simultaneously in a single battle.
Category: Challenger Challenger
Achievement Back for Second
Back for Second • “You have defeated all the prime bosses twice!”
Defeat all of the Mechanical bosses twice. PlayStation 3

History

See the individual mechanical bosses' articles for more specific changes.
  • Desktop 1.2.4: Fixed bug where "The jungle grows restless" message would appear before you have beaten all three mechanical bosses.
  • Desktop 1.2.3.1: No longer spawn randomly if another boss is alive. You can still summon multiple bosses manually.
  • Desktop 1.2.1: Reduced the chance for a mechanical boss summoning item to drop during Hardmode.
  • Desktop 1.2.0.3:
    • Hardmode Crimson, Corruption, and Hallow spread is now slowed after killing Plantera instead of any mechanical boss.
    • Slightly increased the chance for a Solar Eclipse to happen, but they will now only happen after killing a mechanical boss.
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