Chichimec

Flyby. The chichimec doesn't provoke opportunity attacks when it flies out of an enemy's reach.

Regeneration. The chichimec regains 10 hit points at the start of each of its turns, so long as it has 1 hit point.

Divine Resistance. Whenever the chichimec fails a saving throw, it can choose to succeed instead. Whenever the chichimec succeeds on a saving throw in this manner, it regains two less legendary actions at the start of its next turn.

Titan. As a titan, the chichimec's attacks are considered magical, it has advantage on saving throws against spells and other magical effects, it cannot have it's form changed against its will, and it cannot be targeted by divination magic or be perceived through scrying sensors.

Multiattack. The chichimec makes three attacks: one with its Primary Wings, one with its Secondary Wings, and one with its Tail. The chichimec then uses Spellcasting.

Tail. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 20 (2d10 + 9) piercing damage. If the target is a creature, it must make a DC 22 Charisma saving throw or have its Charisma score reduced by 1d4 until it finishes a Long Rest. A creature that has its Charisma score reduced to 0 dies.

Primary Wings. Melee Weapon Attack: +16 to hit, reach 5 ft., one target. Hit: 22 (2d12 + 9) bludgeoning damage. If the target is a creature, it must make a DC 22 Constitution saving throw or be stunned until the end of the chichimec's next turn.

Secondary Wings. Melee Weapon Attack: +16 to hit, reach 5 ft., one target. Hit: 18 (2d8 + 9) bludgeoning damage.

Spellcasting. The chichimec casts one of the following spells without providing material components, using Charisma as the spellcasting ability (save DC 22, +14 to hit with spell attacks):
At will: chromatic orb (lightning damage only), darkness, telekinesis
1/day each: call lightning, chain lightning, control weather (as an action), greater invisibility, lightning bolt

Summon Elemental (Recharge 4-6). The chichimec summons a air elemental myrmidon into an unoccupied space it can see within 300 feet of it. An elemental summoned in this manner acts in initiative immediately after the chichimec. The chichimec can take this action 3 times per Long Rest.

Wing Shield. As a reaction to being hit by an attack, the chichimec can reduce the incoming damage by 22 (4d10).

The chichimec can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The chichi regains spent legendary actions at the start of its turn.

Strike. The chichimec makes a Primary Wing attack.

Will of the Skies (Costs 2 Actions). The chichimec makes a Tail attack, or uses Spellcasting.

Summon Myrmidon (Costs 3 Actions). The chichimec recharges, or uses its Summon Elemental action.