Demon Key

The Demon Keys (sometimes called Demon Artifacts) were special items found only in Doom 64. Their primary use during the game is to upgrade the firepower of the Unmaker. However, they are also used in the final level (The Absolution) to disable the demon teleporters in the level. There are 3 of them (each in a color: golden, pink, and blue), and they are all found in secret levels (29, 30 and 31).