The Mask of Undeath was a Kanohi that siphoned off a tiny part of its user's life-force from their body, which it then used to reanimate their body after they died. When killed, the dead body was then animated by the collected life-force and continued its previous objective from life. The mask gave the user no other power and actually slowed down their thinking and movement. While undead, the user lost all illumination in their eyes.