Yuan-ti Anathema

The anathema has advantage on saving throws against spells and other magical effects.

Any creature of the anathema's choice, other than a snake or a yuan-ti, that starts its turn within 30 feet of the anathema and can see or hear it must succeed on a DC 17 Wisdom saving throw or become Frightened of snakes and yuan-ti. A Frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to this aura for the next 24 hours.

The anathema can use its action to polymorph into a Huge giant constrictor snake, or back into its true form. its statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed.

The anathema has advantage on Wisdom (Perception) checks and on saving throws against being Blinded. Charmed, Deafened, Frightened, Stunned, or knocked Unconscious.

The anathema makes two claw attacks, one constrict attack, and one Flurry of Bites attack.

Melee Weapon Attack +10 to hit, reach 10 ft., one target. 13 (2d6 + 6) Slashing damage.

Melee Weapon Attack +10 to hit, reach 15 ft., one Large or smaller creature. 16 (3d6 + 6) Bludgeoning damage plus 7 (2d6) Acid damage, and the target is Grappled (escape DC 16). Until this grapple ends, the target is Restrained and takes 16 (3d6 + 6) Bludgeoning damage plus 7 (2d6) Acid damage at the start of each of its turns, and the anathema can't constrict another target.

Melee Weapon Attack +10 to hit, reach 10 ft., one creature. 27 (6d6 + 6) Piercing damage plus 14 (4d6) Poison damage.