Meat

Hellhounds breed with other hellhounds, dogs, caninians. Offspring will be hellhounds except with caninians (offspring are half-demons).

Hellhounds, to get to the meat of it, explode when they are killed. Big, fiery explosions that generally kill everyone around them. Furthermore, fire doesn't hurt them at all--mundane or magical. Only Gifted Fire has a chance of hurting them, & then it generally just makes them explode. Furthermore, they have a howl that will freeze people in their tracks. To top that off, they breath fire, albeit very weakly. To summon a hellhound one needs must succeed versus a difficulty of 7 in darkness magic or faith. Hellhounds cannot be controlled by other demons innately, but they will obey the commands of greater fiends & better for the most part. Furthermore, hellhounds leave footprints on stone surfaces, distinct black chars that continue to burn for days after the hound has been there. They do not generally leave footprints on other surfaces, except for on the husks of trees that they themselves destroyed.

Hellhounds, unlike grims, are intelligent & can talk. They are vicious killers, living in packs, eating just about any form of living thing. They do not starve, ever. Thus, those that serve greater demons are generally kept ravenous until they are needed to kill something. Very few hellhounds exist without masters, & those that do are rogues, outcasts, marked for death by other hellhounds. Very little will get in the way of a pack hunting down a rogue. Packs range from 10 to 100 hounds, lead by an alpha male that is generally the toughest of the lot, though sometimes a clever hound or an older but feared hound will lead. If any of the hounds in the pack have magic, they are generally the alpha or his closest crew.