Smagug the Dracohydra
Smagug is a vile and terrifying monster, a crossbreed between a red dragon and a hydra known as a dracohydra. Far larger than most of his kin, he makes up for his lumbering awkwardness with surpassing might.
Smagug makes his home in a very old, but still active, volcanic caldera full of poisonous vapors and boiling hot springs, many of of which are sulfuric acid. He does not lair in a cave, but beneath the open sky, for he has no need to fear the elements. His caldera is, however, dotted with rocky outcroppings and upthrust pillars of sharp stone that could collapse at any moment . . . And will, when he desires it. His three heads often argue with one another, but they focus on a single purpose when something threatens him or looks edible.
Smagug is served by an entire large clan of red scaled Truescale Kobolds who are resistant to acid, fire, and poison.