Biome Chests - Official Terraria Wiki

Defeat Plantera for the first time to lift the curse from Biome Keys, allowing them to be used. As long as Plantera has not been killed, Biome Keys display the tooltip "It has been cursed by a powerful Jungle creature".Obtain the appropriate Biome Key by killing enemies within their respective biome. On Old-gen console and 3DS, the keys are crafted using Key Molds dropped by these enemies.Return to the Dungeon and find the appropriate Chest for the key that was obtained.