Xeraxeash

Hunter. Xeraxeash can sense edible creatures in a 100 foot radius.

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

Spellcasting. Xeraxeash is an 20th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 27, +19 to hit with spell attacks). The aboleth sovereign has the following wizard spells prepared:

Cantrips (at will): Melf's acid arrow, prestidigitation, ray of frost, encode thoughts, minor illusion

1st level (5 slots): detect magic, magic missile, shield,  disguise self

2nd level (4 slots): mind spike, detect thoughts, invisibility, mirror image

3rd level (4 slots): major image, tidal wave, dispel magic, fireball

4th level (4 slots): hallucinatory terrain, dimension door, phantasmal killer

5th level (4 slots): dream, scrying, mislead

6th level (3 slots): mental prison, globe of invulnerability, Programmed Illusion

7th level (3 slots): mirage arcane, simulacrum

Multiattack. Xeraxeash makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 21 (3d10 + 2) piercing damage plus 12 (1d10 + 6) psychic damage. 

Claw. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 17 (3d6 + 5) slashing damage.

Breath Weapons (Recharge 5–6). The dragon uses one of the following breath weapons.

Cold Breath. Xeraxeash exhales an icy blast in a 30-foot cone. Each creature in that area must make a DC 17 Constitution saving throw, taking 54 (12d8) cold damage on a failed save, or half as much damage on a successful one.

Stun Breath. Xeraxeash exhales astral wind in a 50-foot cone each creature in that area must make a DC 17 wisdom saving throw or be stunned for 2 minutes.

Dodge. Xeraxeash can take dodge as a reaction. 

Xeraxeash 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. Xeraxeash regains spent legendary actions at the start of its turn.

Detect. Xeraxeash makes a Wisdom (Perception) check.

Wing Attack (Costs 2 Actions).Xeraxeash beats his wings. Each creature within 10 feet of Xeraxeash must succeed on a DC 21 Dexterity saving throw or take 15 (2d6 + 8) bludgeoning damage and be knocked prone. Xeraxeash can then fly up to half his flying speed.