Avatar of Black Maw

Charge. If the avatar moves at least 10 feet straight toward a target and then hits it with a gore attack on the same turn, the target takes an extra 18 (4d8) piercing damage. If the target is a creature, it must succeed on a DC 18 Strength saving throw or be pushed up to 10 feet away and knocked prone.

Labyrinthine Recall. The avatar can perfectly recall any path it has traveled.

Reckless. At the start of its turn, the avatar can gain advantage on all melee weapon attack rolls it makes during that turn, but attack rolls against it have advantage until the start of its next turn.

Magic Resistance. The avatar has advantage on saving throws against spells and other magical effect.

Siege Monster. The avatar deals double damage to objects and structures.

Rampage. When the avatar reduces a creature to 0 hit points with a melee attack on its turn, the avatar can take a bonus action to move up to half its speed and make a bite attack.

Plague Blood. The avatar is immune to diseases and any effect that would reduce its maximum hit points.

Multiattack. The avatar makes two attacks: one with its greataxe and one with its gore or its bite.

Cursed Greataxe. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 17 (2d12 + 4) slashing damage and the target must make a DC 17 Constitution saving throw or is subject to a random effect from the spell Contagion.

Gore. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 18 (3d8 + 4) piercing damage.

Bite. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 18(3d8+4) piercing damage and the target must make a DC 17 Constitution saving throw or is subject to a random effect from the spell Contagion.

The avatar can take 3 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 avatar regains spent legendary actions at the start of its turn.

Cursed Bite. The avatar makes on bite attack.

Move. The avatar moves up to half its speed without provoking opportunity attacks.

Breath of Disease (3 actions). The avatar unleashes a swirling cloud of vile pestilence and disease in a cone 60-foot cone. Each creature in that area must succeed on a DC 17 Constitution saving throw or is subject to a random effect from the spell Contagion.