Magic Lantern

Type	Light pet
Use time	20 (Very fast)
Tooltip	Summons a magic lantern that exposes nearby treasure
Rarity
Buy	10
Sell	2
Research	1 required
Buff	Magic Lantern
Buff tooltip	An enchanted lantern is lighting your way
Use

Desktop/Console/Mobile-Only Content: This information applies only to the Desktop, Console, and Mobile versions of Terraria.

The Magic Lantern revealing Gold Chests and Gold Ore. Note how the effect shows through walls as well.

The Magic Lantern is a light pet item that summons a small glowing lantern which hovers above the player, emitting dim light. The lantern will also expose all treasure within 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.

Tips

The Magic Lantern can be farmed by creating a new world, getting to the cavern layer, and looking for the Skeleton Merchant until the morning after the first night (the first night after creating a new world will always be a full moon), then creating a new world. This way the player can make sure that when they find the Skeleton Merchant he has the Magic Lantern.
Alternatively, a slower but very reliable method is to wait for the full moon when the player find the Skeleton Merchant. This can be done by trapping him on screen ( and sleeping in a bed to accelerate time) until full moon. This option is better pursued when in possession of a Cell Phone, PDA, Fish Finder or Sextant.