Terrifying entity from Edward's dreams
Nightmare was a monstrous creature dwelling within the Dome of Nightmares. A freakishly fast-moving and violent creature, Nightmare was elongated and emaciated, with the face of some terrifying Mahakala mask.
When he was a child, Edward Grey had a recurring nightmare about a creature with hideously long limbs and a tribal mask for a face.
Though the nightmare was long forgotten by the time he came to Yokurgin, Edward began to suffer from the dreams again. Within the Dome of Nightmares, he encountered a physical representation of the creature, but with the help of his friends, defeated it once and for all.