Hell hounds are fire-breathing canines from another plane of existence brought here in the service of evil beings.

A hell hound resembles a large hound with rust-red or red-brown fur and red, glowing eyes. The markings, teeth, and tongue are soot black. It stands two to three feet high at the shoulder, and has a distinct odor of smoke and sulfur. The baying sounds it makes have an eerie, hollow tone that send a shiver through any who hear them.

Combat: Hell hounds are clever hunters that operate in packs. They do not bay like normal dogs while hunting. They move with great stealth, imposing a -5 penalty to opponents’ surprise rolls. One or two of the pack sneak up on a quarry while the others form a ring around it. The first hell hound then springs from ambush, attacks the nearest victim, and attempts to drive the others toward the rest of the pack. If the prey does not run away, the rest of the pack closes in within 1d4+2 rounds. If hell hounds are pursuing fleeing prey, they might bay.

Hell hounds attack first by breathing fire at an opponent up to 10 yards away. The fire causes 1 point of damage for each of the hell hound·s Hit Dice. A successful saving throw vs. breath weapon cuts the damage in half. The hell hound then attacks with its teeth. The hell hound can continue to exhale flame while biting. If the hell hound rolls a natural 20 on its attack roll, it grabs a victim in its jaws and breathes fire on the victim.

Hell hounds have a variety of defenses. They are immune to fire. Their keen hearing means they are surprised only on a 1 or 2 on 1d10. They can also see hidden or invisible creatures 50% of the time.

Habitat/Society: Hell hounds are native to those extradimensional planes notable for their hot, fiery landscapes. There they roam in packs of 2d20 beasts. The hell hounds on the Prime Material plane are summoned there to serve the needs of evil creatures. Most of them later escape to the wild.

Hell hounds may have 4 to 7 (1d4+3) Hit Dice. The more Hit Dice a hell hound has, the larger it is and the more damage it causes. Each pack is led by a 7-Hit Die hell hound. The leader drives off other 7 HD rivals, who form their own packs.

The diet of hell hounds is similar to that of normal canines. They roam a wide area of 1d10+4 square miles centered on their den. Pack territories may overlap.

They do not easily reproduce on the Prime Material plane. Only 5% of encounters include puppies. Such puppies are born in litters of 2d4. They burp flame uncontrollably at least once a day. The flames are harmless aside from the tendency to set fire to anything flammable in the area. Newborn puppies are at 10% of the adult growth; they quickly grow an additional 5% each month and reach full adult growth (4 HD) in 1½ years. While growing they can attack with their incendiary bite. Hell hound puppies up to two months old inflict 1 point of damage. Older ones add an additional 1 point for each additional six months of growth.

Prey is usually eaten where it is slain, though hell hounds occasionally haul a carcass back to their den for later meals. Hell hounds are also similar to normal canines in that they may act as retrievers. Some objects are specifically sought; this is especially the case in trained hell hounds. Other hell hounds are simply playful and use the retrieved items as toys. They especially like noisy bags and pouches filled with their late victims’ treasures. Flammable containers eventually burn and spill their contents in or around the den. Parchments are rarely found here unless protected by nonflammable containers.

Ecology: Hell hounds have little place in the ecology of the normal world. They are dangerous annoyances prone to cause fires wherever they hunt. Hell hounds cause more forest fires than any other creature except for humanoids. Hell hounds have their uses, though. Because of their ability to easily detect hidden or invisible creatures, hell hounds make excellent watch dogs, especially for intelligent monsters such as fire giants.

Hell hounds can be domesticated if raised from puppies, but there is a 10% chance each year that domesticated hell hounds go wild.