Biome Chests

A Dungeon Chest can be opened with a Dungeon Key of the same color. They have a 1 in 4000 drop chance in their Underground Biome (e.g. Frost Key in Snow Biome).

The key drops from random mobs but only when hard mode has been enabled will the key be a possible drop.

Loot
Besides the common items listed here they have the common items depending on the height they were found: Surface, Underground or Caverns. It can only contain the Eater's Bite in a Corrupt world and only the Vampire Knives in a Crimson world