Apophia, the Emerald Chaos

Deadly Critical. Apophia scores a critical hit on a roll of 19 or 20 and rolls the damage dice three times, instead of twice.

Innate Spellcasting. Apophia’s spellcasting ability is Wisdom (spell save DC 22). She can innately cast the following spells, requiring no material components:

At will: detect thoughts, dispel magic, vitriolic sphere

1/day each: Abi-Dalzim’s Horrid Wilting

Legendary Resistance (3/Day). If Apophia fails a saving throw, she can choose to succeed instead.

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

Whirlwind of Venom. A magical aura of poison surrounds Apophia in a 10 foot radius. At the start of each of her turns, any other creature in the aura takes 14 (4d6) poison damage.

Multiattack. Apophia makes three melee attacks of her choice and one spell or Chaotic Purge attack.

Acidic Scimitar. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 21 (4d6+7) acid damage. Any creature killed by this attack is dissolved after 1 minute.

Bite. Melee Weapon Attack: +16 to hit, reach 5 ft., one creature. Hit: 14 (2d4+9) force damage, and the target must succeed on a DC 22 Constitution saving throw or take 13 (2d12) poison damage and become poisoned until it finishes a short or long rest. The target’s hit point maximum is reduced by an amount equal to half the poison damage taken. This reduction lasts until the poisoned condition is removed. The target dies if its hit point maximum is reduced to 0.

Tail. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 20 (2d10+9) force damage. If the target is a Large or smaller creature, it is also grappled (escape DC 24), and it is restrained until the grapple ends. Apophia can grapple only one creature with her tail at a time.

Chaotic Purge ((Recharge 6)). Apophia strikes the ground, creating a burst of noxious energy that ripples outward from her. Each creature she chooses within 30 feet of you must succeed on a DC 22 Constitution saving throw or take (5d6) acid damage, as well as (5d6)poison damage, and becomes blinded and poisoned for one minute and gains one point of exhaustion. A creature that succeeds on its saving throw takes half as much damage and does not become blinded and poisoned for one minute and does not gain one point of exhaustion.

Apophia can take 4 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. Apophia regains spent legendary actions at the start of her turn.

Attack. Apophia makes one melee or spell attack attack.

Destroy Magic (Costs 2 Actions). Apophia casts dispel magic.