Black Cage Key

Black Cage Keys can be found on the corpses of and  upon Deathspeaker's Watch west of the Argent Tournament Grounds in Icecrown.

The keys are used to open Black Cages in the /-level daily quest You've Really Done It This Time, Kul (Alliance) / (Horde) where players are tasked to free four Captive Aspirants and Kul the Reckless.