Anathema Homebrew

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

Slither Strike. Other creatures can't take reactions on the Yuan-Ti's turn.

Spellcasting. The Anathema is a 9th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 17, +9 to hit with spell attacks). The Anathema has the following spells prepared:
Cantrips (at will): poison spray, firebolt, mending, chill touch, mage hand 
1st level (4 slots): shield, magic missile, false life

2nd level (3 slots): hold person, misty step

3rd level (3 slots): counterspell, fireball

4th level (3 slots): polymorph

5th level (1 slots): dominate person

Multiattack. The Anathema makes one claw attack and either one constrict attack or one flurry of bites attack

Claw. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit:  (2d6 + 6) slashing damage.

Constrict. Melee Weapon Attack: +10 to hit, reach 15 ft., one large or smaller creature. Hit:  (2d6 + 6) bludgeoning damage plus (2d6) acid damage, and the target is grappled (escape DC 16). Until this grapple ends the target is restrained and takes this damage again at the start of their next turn

Flurry of Bites. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit:  (2d6 + 6) piercing damage plus (4d4) poison damage.

Poison Essence (1/day). All creatures in a 15ft cone musk make a DC 17 Constitution Saving Throw. On a failed save the target take (10d10) poison damage, or half as much on a success. If the target is reduced to 0 HP, they also have their constitution score reduced by 3d6. If the target is a Yuan-Ti, it makes the saving throw with disadvantage.

Force of Nature. Anathema may cast polymorph as a bonus action 

Divine Backlash. When the Anathema passes a saving throw against a magical effect, it may use its reaction to deal (3d8) radiant damage to the spellcaster.

Enter the description for how legendary actions work for your monster here.

Legendary Action Name (Costs # Actions). Enter the description for your legendary action.

Mythic Action Name. Enter the description for how mythic actions work for your monster here.

Mythic Action Name (Costs # Actions). Enter the description for your mythic action.