Mechanical Skull

The Mechanical Skull is used to summon Skeletron Prime, the hardmode version of Skeletron. It can only be used during night time. Using another Mechanical Skull while Skeletron Prime is alive will not consume the skull, and a second Skeletron Prime will not be summoned. It can also be used in a world without hardmode activated. If you have not defeated Skeletron Prime yet and are already in hardmode, all enemies (with the exception of statue-spawned enemies and meteor heads) have a 1 in 2500 (0.04%) chance of dropping this item.

Trivia

 * Can be dropped by a purple slime that appears to be changing between purple and green, but displays the purple slime name and size.
 * The Skull Lantern and Mechanical Skull are very similar in appearance to the skull in the original sprite for Skeletons: Skeleton (original).gif.
 * Like the Mechanical Worm, it looks like a wind-up toy.

History
Crâne mécanique 기계식 두개골