Bone Anathema

Innate Spellcasting (Anathema Form Only). The anathema’s innate spellcasting ability is Charisma (spell save DC 17). It can innately cast the following spells, requiring no material components:

At will: animal friendship (snakes only)

3/day each: darkness, entangle, fear, haste, suggestion, polymorph

1/day: divine word

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

Ophidiophobia Aura. 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.

Six Heads. The anathema has advantage on Wisdom (Perception) checks and on saving throws against being blinded, charmed, deafened, frightened, stunned, or knocked unconscious.

Turn Immunity.The anathema is immune to effects that turn undead.

Enchanted Pendant. The anathema has a jade serpent pendant that grants necrotic resistance.

Legendary Resistance (1/Day). If the Anathema fails a saving throw, it can choose to succeed instead.

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

Claw . Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 11 (2d6 + 5) slashing damage.

Constrict. Melee Weapon Attack: +9 to hit, reach 15 ft., one Large or smaller creature. Hit: 20 (5d6 + 5) piercing damage, and the target is grappled (escape DC 16). Until this grapple ends, the target is restrained and takes 14 (3d6 + 5) piercing damage at the start of each of its turns, and the anathema can’t constrict another target.

Flurry of Bites. Melee Weapon Attack: +9 to hit, reach 10 ft., one creature. Hit: 26 (6d6 + 5) piercing damage plus 14 (4d6) poison damage.

The Bone Anathema is a lost god-like entity to an ancient civilization, over time the scales and flesh sloughed off and the bones were all that remained. The essence of their worship is what gifted them some grasp on life beyond mortal death. It can take 3 legendary reactions from the following list.

Slither (Costs 1 Action). The Anathema can move up to its speed without provoking opportunity attacks.

Toothed Dagger (Costs 2 Actions). The Anathema pulls out a tooth and makes a ranged attack with it. +5 to hit, Hit: 7 (2d4+1) piercing and 3 (1d6) poison damage.

Summon Spectral Snakes (Costs 3 Actions). The Anathema summons 1d4 giant spectral snakes on any creatures it chooses within 60ft that it can see. The creature must make a DC 15 Intelligence save on a failure the creature takes 2d6 psychic damage, on a success the creature takes no damage. Once the snake attacks, it immediately disappears.