Elemental Body. Aaastedres's AC increases by 3, and he has immunity to acid, cold, fire, lightning, poison, and thunder damage. 

Multiattack. Aaastedres can use his Create Elemental. He then makes five attacks: one with his Earth Rock, two with his Fire Slam, and two with his Water Jet.

Fire Slam. Melee Weapon Attack: +19 to hit, reach 20 ft., 1 target. Hit: 28 (4d8 + 10) bludgeoning damage + 14 (4d6) fire damage. 

Earth Rock. Ranged Weapon Attack: +19 to hit, range 300/500 ft., 1 target. Hit:  42 (5d12 + 10) bludgeoning damage plus 7 (2d6) acid damage.

Water Jet. Aaastedres shoots water in a 5 foot wide, 200 foot long jet. Anything in the line must make a DC 19 Dexterity saving throw, taking 42 (12d6) bludgeoning damage on a failed save, or half as much on a successful one.

Harness the Air (Recharge 5-6). Aaastedres conjures a storm cloud that flies directly toward his enemies, shooting them with lightning and assailing their ears with thunder. Each creature other than Aaastedres in a 300 foot cylinder must make both a DC 19 Dexterity saving throw to avoid the lightning, and a DC 19 Constitution saving throw against the thunder. On a failed Dexterity save, a target takes 22 (4d10) lightning damage, or half as much on a successful save, while on a successful Constitution save, a creature takes half of 22 (4d10) thunder damage.

Create Elemental (4/day). Aaastedres creates a dao, a djinni, an efreeti, or a marid to aid him in confronting his enemies. Once he has created a genie, he cannot create the same type of genie until he finishes a long rest. A summoned genie stays until it dies or until the next dawn.

Combine Elements. If an attack would hit Aaastedres, he can use his reaction to add 4 to his AC, potentially turning the hit into a miss.

Aaastedres can take three legendary actions. Only one legendary action can be used at a time, and only at the end of another creature's turn. Aaastedres regains spent legendary actions at the start of his turn.

Master of Elements (Costs 2 Actions). Aaastedres uses his Create Elemental.

Steam Cloud (Costs 2 Actions). Aaastedres uses both Water Jet and Fire Slam.

Call the Storm (Costs 3 Actions). Aaastedres uses Harness the Air.