Apex Venom Hound

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

Opportunistic Strike. The Apex Venom Hound has advantage on opportunity attacks made against creatures attempting to move through its space.

Wakeful. While the Venom Hound sleeps, at least one of its heads is awake.

Multiple Heads. The Venom Hound has four heads. While it has more than one head, the Venom Hound has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Reactive Heads. For each head the Venom Hound has beyond one, it gets an extra reaction that can be used only for opportunity attacks.

Magic Resistance. The Apex Venom Hound has advantage on saving throws against spells and other magical effects.

Multiattack. The Apex Venom Hound can make four bite attacks, three with its three heads and one with the head on its tail or four venom spray attacks.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 55 (7d10 + 13) Piercing damage and 26 (4d8 + 6) Poison damage. Targets hit by this attack must make a DC 18 Constitution Saving Throw or be poisoned until the poison is cured.

Venom Spray. Ranged Weapon Attack: +9 to hit, reach 60/90 ft., 1 target. Hit 37 (5d10 + 7) Poison damage and the target is blinded.

Toxic Breath (Recharge 6). The Apex Venom Hound exhales poisonous gas in a 30-foot cone. Each creature in that area must make a DC 17 Constitution saving throw, taking 50 (10d8) Poison damage on a failed save, or half as much damage on a successful one.