Uro

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

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

Titanic Fortitude. Uro has advantage on Constitution saving throws to maintain concentration.

Siege Monster. Uro deals double damage to objects and structures.

Unrelenting Storm (Mythic Trait; recharges after a Short or Long Rest). When Uro is reduced to 0 hit points, he doesn't die or fall unconscious. Instead, he regains 646 hit points and casts storm of vengeance, even if he already has cast it before finishing a long rest. Uro can't lose concentration on this spell, even if he casts another spell that requires concentration.

Innate Spellcasting. Uro's spellcasting ability is Constitution (spell save DC 26, +18 to hit with spell attacks). He can innately cast the following spells requiring no material components: 

At will: thorn whip(17th level), entangle, warding wind, control water, control winds, control weather

3/day each: lightning bolt, sleet storm, tidal wave, watery sphere, transmute rock, wall of thorns

1/day each: maelstrom, wrath of nature, chain lightning, whirlwind, tsunami, storm of vengeance, 

Multiattack. Uro makes three with his fists.

Multicast. Uro casts two spells of his choice, but they can't be the same spell.

Fist. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 28 (4d8 + 10) bludgeoning damage.

Uro can take 3 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. Uro regains spent legendary actions at the start of her turn.

Attack. Uro makes a fist attack.

Lashing Vines. Uro casts thorn whip (17th level).

Move. Uro moves up to half his speed.

If Uro's mythic trait is active, he can use the options below as legendary actions for 1 hour after using Unrelenting Storm.

Nature's Fury. Uro makes a fist attack and casts a spell.

Hurricane (Costs 2 Actions). Each creature within a 30-foot-radius, 100-foot-high cylinder of Uro must make a DC 25 Strength saving throw, taking 12 (3d8) force damage on a failed save or half as much damage on a successful one. In addition, a Huge or smaller creature that fails the save is sent to the top of the cylinder surrounding Uro.