Yuurei

The Yuurei is an pre-Hardmode enemy that spawns in the Pagodas. It floats around idly until provoked by the player, after which it will chase the player and occasionally teleport in a cloud of smoke. Its stats scale upon killing Pre-Hardmode bosses.

Trivia

 * Yuurei is based off of the Gosmet from the action-adventure game Starbound.