Key of Light

Placing this inside an empty chest will turn it into a Hallowed Mimic. Its counterpart is the Corrupt Mimic, done the same except with a Key of Night.

Autopause must be disabled for this to work, and Hardmode must be enabled. The key must also be the only item remaining in the chest.

Bugs

 * Placing the Key of Light in an empty chest and then opening another chest without closing the inventory will not spawn the Hallowed Mimic.

History
Clé de la Lumière