Cerberus

Three-Headed: Cerberus has advantage on Wisdom (Perception) checks and on saving throws against being blinded, deafened, stunned, or knocked unconscious.

Innate Spellcasting: Cerberus’ innate spellcasting ability is Wisdom (spell save DC 15). It can innately cast the following spells, requiring no material components.

At will: Speak with Dead

3/day: Animate Dead, Protection from Evil and Good

1/day: Circle of Death, Wall of Force

Multiattack. Cerberus can make three bite attacks.

Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 30 (4D10 + 8) piercing damage. If the target is a Medium or smaller creature, it is grappled (escape DC 20). Until this grapple ends, the target is restrained. Cerberus, can make a bite attack as long as one of its mouths are free. If its center head makes the bite attack, it deals an additional 11 (2D10) fire damage.

Fire Breath (Recharge 5–6). Cerberus exhales fire from its central headin a 60-foot cone. Each creature in that area must make a DC 16 Dexterity saving throw, taking 35 (10D6) fire damage on a failed save, or half as much damage on a successful one.