A Nightmare Demon with a basic human appearance hiding a hellish deathmask which is revealed in combat.
Demons are hell spawn. Nightmare Demons also inhabit the dream realm, where reality is malleable, so are adept at controlling their surroundings and appearance, though when they are corporeal, this is mostly accomplished through controlling the minds of others.
Amity works to appear pleasant until entrenched in battle when she reveals a horrifying countenance to panic enemies. Allies will inevitably see this face as well, demons do not distinguish between friends and enemies. All are marked for eventual sacrifice. Amity, unlike some of her demonic brethren, is perfectly comfortable living among mortals and will often join the quests of others for years before she turns her true aspect on them. Demons are never easily trusted, so she has learned to be patient, waiting until suspicion is lessened before annihilating those around her. Betrayal, though inevitable, is still difficult to predict, for she will render assistance willingly, even eagerly, until she feels it is time, and then she will burn their lives down. Her friends and victims, always one and the same, have usually seen her work on enemies several times before they find themselves under her knife, so they know just what horrors await them, and she delights in their fear as much as in the heinous rites themselves.