Arias Vayu, high air elemental

Air Form. The elemental can enter a hostile creature's space and stop there. It can move through a space as narrow as 1 inch wide without squeezing.

Wind walker. The arias vayu can move through the air, teleporting itself up to 90 feet with its movement speed and ignoring attacks of opportunity.

Legendary Resistance (3/Day). If the elemental fails a saving throw, it can choose to succeed instead.

Spellcasting. The elemental is an 18th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 20, +12 to hit with spell attacks). The elemental has the following  spells prepared:

Cantrips (at will): Shocking grasp.

1st level (4 slots): Thunderwave, Witch bolt.

2nd level (3 slots): Gust of wind, Misty step, Shatter.

3rd level (3 slots): Call lighting, Lighting bolt. Wind wall.

4th level (3 slots): (For leveled spells)

5th level (3 slots): Destructive wave.

6th level (1 slot): Chain lighting, Wind walk.

7th level (1 slot): Teleport.

8th level (1 slot): Control weather

9th level (1 slot): Storm of vengeance

Wind blade. Ranged Weapon Attack: +12 to hit, range 150 ft., one target. Hit: 15 (2d10 + 5) slashing damage. If the target is a creature that wears armor, the attack will ignore two points of AC.

The elemental 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. The elemental regains spent legendary actions at the start of its turn.

Crystal of wind. A strong wind covers the arias vayu, forcing disadvantage on the next attack roll that targets the elemental and if the attack (Not only the attack from the weapon but also additional damage, like a coated weapon with poison)

Crystal of lighting. A lighting bolt falls in a point within 60 feet radius. Each creature within 5 feet of that point must make a Dexterity saving throw. A creature takes 3d10 lightning damage on a failed save, or half as much damage on a successful one.

Crystal of Typhoons (Cost 2 Actions). Each creature within 30 feet of the elemental must make a DC 16 Strength saving throw. On a failure, a target takes 15 (3d8 + 2) bludgeoning damage and is flung up 20 feet away from the elemental in a random direction and knocked prone. If a thrown target strikes an object, such as a wall or floor, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 13 Dexterity saving throw or take the same damage and be knocked prone.

If the saving throw is successful, the target takes half the bludgeoning damage and isn't flung away or knocked prone.

Crystal of thunder (Cost 2 Actions). The arias vayu becomes hasted the next round. At the start of the next round the elemental increases its AC by 2, its iniciative by 20 and it gains an additional standard action.