Hellhound

Monstrous, cunning, and very intelligent hounds, the size of a small pony. Breathe fire and love heat. Dwell in dungeons or near volcanoes.

AC4 [15], HD3 to 7* (13 / 18 / 22 / 27 / 31hp),
Att 1 × bite (1d6) or 1 × breath (1d6 per HD), THACO By HD (17 [+2] to 13 [+6]),
MV 120’ (40’), SV By HD,
ML 9, AL Chaotic, XP 50 / 125 / 300 / 500 / 850, NA 2d4 (2d4), TT C

• Fire breath: 2-in-6 chance per round of breathing fire. One target. Save versus breath for half damage.
• Fire immunity: Unharmed by non-magical fire.
• Detect invisible: 75% chance per round. 60’ range.
• Pets: Sometimes found with other creatures with an affinity for fire.

Source: Classic Fantasy