Dark Keeper Key

The Dark Keeper Key drops from one of six possible Dark Keepers which spawn after a party member looks at the portrait in the Black Vault anteroom. This key is needed to open the Dark Coffer in the Black Vault. Each Keeper spawns in a different location, which the portrait gives clues to.

Source
This item drops from:
 * Dark Keeper Bethek in Blackrock Depths
 * Dark Keeper Pelver in Blackrock Depths
 * Dark Keeper Zimrel in Blackrock Depths
 * Dark Keeper Uggel in Blackrock Depths
 * Dark Keeper Ofgut in Blackrock Depths
 * Dark Keeper Vorfalk in Blackrock Depths