There are 5 different kinds of keys that can be found and used in Blackrock Depths:
- Relic Coffer Key for opening Relic Coffer Doors in the Black Vault and drop from mobs throughout the instance
- Prison Cell Key is used indirectly for some quests and drops from High Interrogator Gerstahn <Twilight's Hammer Interrogator>.
- Dark Keeper Key used to open the Dark Coffer in the Black Vault and drops from a random Dakr Keeper spawned after reading the Dark Keeper Nameplate.
- Shadowforge Key opens several doors in the instance and is a reward from the Dark Iron Legacy quest.
- Grim Guzzler Key opens the back door of the Grim Guzzler (may be consumed on use) and is only pickpocketed from Plugger Spazzring.