Lost Mine of Phandelver
Imix, Prince of Evil Fire Creatures, The Eternal and All Consuming Flame, is said to appear as a roughly humanoid pillar of red flame with flaming tendrils that radiates waves of intense heat. He stands 18 feet tall and weighs only 6 pounds. He may also appear as a 20-foot-tall flaming red bull.
Imix’s pyramid-fortress called the Temple of Ultimate Consumption lies within the heart of a massive volcano rising from the liquid flames of the Blazing Sea, upon the Plain of Burnt Dreams, on the Elemental Plane of Fire.