The Death's Head mask was a face mask worn throughout several eras by Mortanius, the Guardian of the Pillar of Death. It was alabaster-white, and seemed to alter the contours of its wearer's face, giving him a gaunt, skeletal visage. The mask sported no eye slots, with only black, empty sockets in their place.
Throughout all of his interfaces with Kain during Blood Omen: Legacy of Kain, Mortanius wore the Death's Head mask, concealing his face. He had also worn it centuries earlier in Avernus Cathedral, when condemning Malek for his failure to defend the Circle of Nine from Vorador.[BO1] Mortanius could easily summon and dismiss the mask through magical means.
In Legacy of Kain: Defiance, during the fourth timeline's Blood Omen era, Mortanius was seen wearing the mask in the Avernus Catacombs while leading the Cenobites in their worship of Hash'ak'gik/Turel. When Raziel confronted Mortanius after slaying Turel, Mortanius dismissed the mask, speaking to the Hylden Champion directly. He donned it again at the end of their discussion, before teleporting away to battle Anarcrothe and Kain at the Pillars of Nosgoth.[DEF]