Vorinclex, the Unquenched

Legendary Resistance (4/Day). If Vorinclex fails a saving throw, he can choose to succeed instead.

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

Unquenchable thirst. Vorinclex drinks a potion at the start of his turn. 

Rebuke Temperance (Recharge 5-6). This effect triggers at the start of Vorinclex's turn. Charisma Saving Throw: DC 21, up to two creatures within 45 ft. that haven't consumed a potion since Vorinclex's last turn. Failure: Targets take 33 (6d10) psychic damage. Success: Half damage only. 

Multiattack. Vorinclex makes one Maw of Hunger attack as well as two Slam attacks.

Maw of Hunger. Melee Attack: +15 to hit, reach 10 ft., one target. Hit: 30 (4d10 + 8) piercing + 14 (4d6) necrotic damage. If the target is Large or smaller, it must make a DC 23 Strength save or become swallowed. While swallowed, the target takes 42 (12d6) acid at the start of each of Vorinclex's turns and is Restrained. Vorinclex can only have 1 large, 2 medium or 3 small creatures swallowed at the same time. 

Slam. Melee Attack: +15 to hit, reach 15 ft., one target. Hit: 34 (4d12  + 8)  bludgeoning damage.

Rotting Breath (Recharge 5-6). Constitution Saving Throw: DC 23, each creature in a 60-foot Cone. Failure: 72 (16d8) Poison damage, and the target becomes Poisoned until the end of it's next turn. Success: Half damage only.

Bottoms up  (Recharge 4-6). Vorinclex drinks another potion. 

Lunge. Vorinclex moves 30 ft without provoking opportunity attacks. 

Digestive Surprise. When Vorinclex takes 30+ damage from a single attack, he can regurgitate a part of his diggestive acid. Every target in a 15 foot cone towards the attacker makes a DC23 Dexterity Saving throw or takes 36 (8d8) acid damage. Half as much damage on a success. 

Induce Thirst. When Vorinclex is targeted by a spell with a single target, the caster makes a DC 21 Wisdom Saving Throw. On a fail, the caster is also affected by the spell. 

Legendary Action Uses: 3. Immediately after another creature’s turn, Vorinclex can expend a use to take one of the following actions. Vorinclex regains all expended uses at the start of each of its turns.

Slam (Costs 1 action). Vorinclex makes one Slam attack. 

Potion Toss (Costs 1 action). Dexterity Saving Throw: DC 20, one creature within 60 ft. Failure: 27 (6d8) Poison damage, and the target has the Poisoned condition until the end of its next turn. Success: Half damage only.

Potion Shield (Costs 1 action - Once per round). Vorinclex smashes a potion to his feet and gains +3 AC until the end of his next turn. 

Taste of the Weave (Costs 3 Actions). Vorinclex dispels a magical effect or ongoing spell within 20 ft. of him. He takes psychic damage equal to 5 x the spell's level.