Underworld Key

The Underworld Key is the only key to the Underworld and is guarded by Thanatos, who, when defeated, drops the key. It is a purple gem with the Underworld Army's symbol in the center. It is used to reach the Underworld and, ultimately, Medusa.

Idol Description
''Held by Thanatos, this jewel unlocks the entrance to the Underworld. Although the Underworld and Overworld seem close, they are quite difficult to cross between. If free passage were allowed, there would be no telling the living from the dead.''