Mechanical Eye

The Mechanical Eye is used to summon The Twins, the advanced and Hardmode version of the Eye of Cthulhu. It can only be used at night, which means consuming this item during day will not spawn The Twins. Using another Mechanical Eye while the The Twins are active will not cause any additional effects, and will not be consumed. It can also be used in a world without Hardmode enabled. If you have not defeated The Twins before dawn, they will flee and you won't be able to finish the fight.

If you have not defeated The Twins yet and are already in Hardmode, all enemies (with the exception of statue-spawned enemies and Meteor Heads) have a 1/2500 (0.04%) chance of dropping this item. It seems that The Twins will more likely to spawn naturally if you meet the requirements (Destroy Demon/Crimson altar) if you have this item in inventory.

Tips

 * Use it just after 7:30 PM, so you have a better chance defeating them.

Trivia

 * The Mechanical Eye is the only mechanical item with no visible start-up mechanism.

History
Œil Mécanique 기계식 눈