Legendary Resistance (3/day): If Zephyrax fails a saving throw, he can choose to succeed instead.

Rift Master. Zephyrax can open temporary rifts between planes at will. As a bonus action, Zephyrax can create a rift within 120 feet of him. This rift can lead to any plane of existence, as determined by Zephyrax. Creatures within 20 feet of the rift must succeed on a DC 22 Dexterity saving throw or be pulled into it. The rift remains open for 1 minute or until Zephyrax closes it as a free action.

Aura of Chaos. Zephyrax exudes an aura of chaotic energy in a 30-foot radius. Any creature that starts its turn in this aura must succeed on a DC 22 Wisdom saving throw or suffer one of the following random effects, determined by rolling a d6:
(1) - The creature is restrained until the start of its next turn.
(2) - The creature takes 4d10 psychic damage.
(3) - The creature is charmed by Zephyrax until the start of its next turn.
(4) - The creature is frightened until the start of its next turn.
(5) - The creature falls prone and is stunned for 1 round.
(6) - The creature is banished to a random plane for 1 minute.

Spellcasting. Zephyrax is a 20th-level spellcaster. His spellcasting ability is Intelligence (spell save DC 23, +15 to hit with spell attacks). Zephyrax has the following sorcerer spells prepared, focusing on mind control, illusions, and manipulating his opponents:

Cantrips (at will): Mage Hand, Eldritch Blast, Thaumaturgy, Mind Sliver, Minor Illusion

1st level (5 slots): Shield, Magic Missile, Detect Magic, Dissonant Whispers, Tasha’s Hideous Laughter

2nd level (4 slots): Mirror Image, Misty Step, Hold Person, Phantasmal Force, Detect Thoughts

3rd level (4 slots): Counterspell, Fireball, Fly, Enemies Abound, Hypnotic Pattern

4th level (4 slots): Greater Invisibility, Dimension Door, Confusion, Phantasmal Killer

5th level (4 slots): Teleportation Circle, Wall of Force,  Dominate Person, Synaptic Static

6th level (3 slots): Chain Lightning, Mental Prison

7th level (2 slots): Plane Shift, Crown of Stars

8th level (2 slots): Dominate Monster

9th level (1 slot): Wish, Power Word Kill

Multiattack. Zephyrax makes three attacks with his Chaosblade Slash or Riftstrike in any combination. He can replace one of these attacks with Chaotic Wave if available.

Chaosblade Slash (Melee Attack). Melee Weapon Attack: +17 to hit, reach 20 ft., one target.
Hit: 45 (6d10 + 12) slashing damage plus 18 (4d8) psychic damage.

Riftstrike (Melee Attack). Melee Weapon Attack: +17 to hit, reach 15 ft., one target.
Hit: 38 (5d8 + 12) slashing damage plus 22 (5d10) force damage. On a hit, a rift in space opens, and the target must make a DC 22 Strength saving throw. On a failed save, the target is pulled 30 feet toward Zephyrax and becomes restrained until the end of its next turn.

Chaotic Wave (Recharge 4-6). Up to 6 creatures that he can see.
The target must succeed on a DC 22 Intelligence saving throw or be overwhelmed by chaotic visions, causing them to suffer disadvantage on all attacks and ability checks until the end of their next turn.  On a fail, the target takes 40 (6d8 + 10) force damage or half on a success.

Distorted Time: Zephyrax can make one additional melee weapon attack as part of his next multiattack action. Additionally, his movement speed increases by 20 feet until the end of his next turn.

Unstable Resonance: The chaotic energy around Zephyrax amplifies his power. Until the start of his next turn, his melee weapon attacks score a critical hit on a roll of 18-20.

Rip Through the Rift. If Zephyrax is targeted by a ranged attack, he can use his reaction to tear open a small rift in space, causing the attack to pass through and target another creature within 30 feet of him instead (the original attack roll is used).

Chaotic Counter. When a creature misses Zephyrax with a melee attack, he can use his reaction to force that creature to make a DC 22 Intelligence saving throw. On a failed save, the creature becomes disoriented and suffers disadvantage on all attacks until the end of its next turn.

Zephyrax 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.

Attack: Zephyrax makes a Rift Strike attack.

Plane Shift (Costs 2 Actions): Zephyrax can shift to any plane of existence and take 2 creatures within 10 feet with him.

Summon Minions (Costs 3 Actions): Zephyrax opens a rift and summons 1d4 minions (such as magmins, vargouilles, or spirit nagas) from the planes to fight by his side.