Ysval was a nighthaunt; a sentient undead being from the Plane of Shadow - an avatar of darkness[1].


Ysval somewhat resembled a gargoyle with bat wings, talons, curling horns and a whipping serpentine tail. His body looked as if made of the shadow-stuff of the night itself. He had no face, just a flat triangular space set with a pair of pale eyes, blank and round as pearls.[2]


Unlike many other undead creatures, Ysval could bear the touch of sunlight without actual harm, though it makes him feel uncomfortable. He had the mystical strength to darken the day to a point where it seemed almost as dark as during the night. When conversing with his underlings, Ysval used a psychic bond for communication without words.[3]


In 1375 DR, Ysval led an army of undead to conquer Thay.[4] He felt kindred spirit Shex, one of his commanders.[1] He was slain by the combined attacks of Bareris Anskuld, Mirror, Aoth Fezim, Milsantos Daramos, and Nymia Focar at the fight of Thazar Keep[5]. There is evidence that he was ultimately destroyed.