Hell hound

A hell hound was a big, powerfully built dog with short, rust-red fur; its markings, teeth, and tongue were sooty black.

Description
Hell hounds were the dogs of the Nine Hells. They appeared to be canines with emaciated features and fire spouting from their red glowing eyes and mouths. The average hell hound stood 4 1/2 ft (1.4 m) at the shoulder and weighed about 120 lb (54.4 m).

Combat
Hell hounds preferred to hunt in packs and would use their fiery breath on an opponent first and then close in for the kill.

Ecology
While hell hounds were found in the Plane of Hell, they were also regularly seen in the Plane of Fire and the mortal world. Fire giants and other fiery creatures made use of hell hounds as guard dogs and hunting beasts.

Society
Hell hounds used wolf-like tactics. They organized in packs, surrounding their prey, and attacked one at a time until the target became fatigued or fell to the ground. If singular attacks did not seem to be effective, the pack would each breathe a gout of flame at the target. The pack then charged in all at once to slay their prey with fiery bites.

Sourcebooks

 * Monster Manual 1st edition
 * Monstrous Manual
 * Monster Manual 3.5
 * Monster Manual 4th edition