Alpha Hell Hound

Relentless Alpha. The hound is immune against being frightened.

Keen Senses. The hound has advantage on Wisdom (Perception) checks that rely on sight, 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.

Multiattack. The hound makes its Fire Breath attack if charged. It then makes three attacks: two bite attacks and one attack with its tail. It can't make a tail and a bite attack against the same target.

Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 13 (3d8 + 8) piercing damage plus 7 (2d6) fire damage. The bitten creature must make a DC 15 Dexterity saving throw or it is grappled. The hound cannot take bite attacks if it is grappling a creature. The grappled creature takes 4 (1d8) piercing damage and 6 (2d6) fire damage at the start of its turn.

Tail Whip. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 20 (1d8 + 8) bludgeoning damage plus 7 (2d6) fire damage.

Fire Breath (Recharge 5-6). The hound exhales fire in a 15-foot cone. Each creature in that area must make a DC 15 Dexterity saving throw, taking 24 (8d6) fire damage on a failed save, or half as much damage on a successful one. If the hound is grappling a creature, that creature automatically takes 48 (16d6) fire damage, and the fire is contained to just that creature.

The hound can take 2 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The aboleth regains spent legendary actions at the start of its turn.

Detect. The hound makes a Wisdom (Perception) check.

Bite. The hound makes one bite attack.

Run. The hound travels its movement.