Artefact found in the hands of a dead archdeacon in a dreamed world.
Found in the room after defeating Melquiades. Used to unlock part of the Archcathedral Rooftops elevator.
Lore
Confession of Orestes
My forces are decreasing. I fear that the sacred mission that your Most Illustrious has entrusted to me is beyond our abilities. The others are mistaken: if the answer were so easily found, I would not have ventured into this place, crossing the boundaries of the flesh. My time, limited as it already was, has not been enough to unravel the unfathomable mysteries of this dream kingdom. This land that my ignorance and pride have turned into my grave.
I find consolation in knowing that the mask will remain with me, thus eluding ungodly hands in the same way that the answers I sought have managed to elude my useless scrutiny.