Keen Hearing and Smell. The hound has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Pack Tactics. The hound has advantage on an attack roll against a creature if at least one of the hound's allies is within 5 feet of the creature and the ally isn't incapacitated.

Bite. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 15 (3d8 + 5) piercing damage plus 15 (3d8+5) Fire, acid, poison, lightning or thunder damage.

Chromatic Breath (Recharge 5–6). The hound exhales Fire, acid, poison, lightning or thunder in a 25-foot cone. Each creature in that area must make a DC 16 Dexterity saving throw, taking 40 (8d8) Fire, cold, acid, poison, lightning or thunder damage on a failed save, or half as much damage on a successful one.