Blue Skeletal Horse

"Mount" is not in the list of possible values (Cloth armor, Leather armor, Mail armor, Plate armor, Axe, Dagger, Fishing pole, Fist weapon, Mace, Miscellaneous, Polearm, Staff, Sword, Bag, Enchanting bag, Engineering bag, Gem bag, Herb bag, Leatherworking bag, Mining bag, Soul bag, Arrow, Bow, Bullet, Crossbow, Gun, Idol, Libram (relic), Shield, Sigil, Thrown, Totem (relic), Wand) for this property.