The Magic Lantern summons a small glowing lantern that flies above the player, emitting dim light. The lantern will also expose treasure for up to 15 tiles from the lantern's location, overlaying sparkles over nearby treasure. It is purchased from the Skeleton Merchant for 10 , during the night of a full moon.
The lantern will always try to maintain a position just forward of and above the player, passing through blocks as needed. If the player gets far enough away, the lantern will propel itself with a rocket exhaust in order to catch up. The lantern's position can block objects of interest at ceiling height, but if the player just turns around, the lantern will move to their other side.
The Suspicious Looking Eye pet has a similar mechanic where it stares at chests and ores.