Innate Spellcasting (Psionics). Vlaakith's innate spellcasting ability is Intelligence (spell save DC 27, +19 to hit with spell attacks). It can innately cast the following spells, requiring no components:

At will: mage hand (the hand is invisible),invisibility, levitate (self only), telekinesis

3/day each: jump, misty step, nondetection (self only)

1/day each: Bigby's hand, mass suggestion, plane shift

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

Limited Magic Immunity. Unless she wishes to be affected, Vlaakith is immune to spells of 3rd level or lower that directly target her. She has advantage on saving throws against all other spells and magical effects.

Regeneration. If Vlaakith has at least 1 hit point, she regains 20 hit points at the start of her turn.

Rejuvenation. If she has a working phylactery, a Vlaakith gains a new body in 1d10 days if she is destroyed, regaining all her hit points and becoming active again. The new body appears within 5 feet of the phylactery.

Spellcasting. Vlaakith is an 20th-level spellcaster. her spellcasting ability is Intelligence (spell save DC 27, +19 to hit with spell attacks). Vlaakith has the following wizard spells prepared (While attuned to the RIng of Supreme Wizardry she can prepared an additional 10 spells and 2 cantrips):

Cantrips (at will): fire bolt, mind sliver, prestidigitation, ray of frost, toll the dead

1st level (4 slots): absorb elements, charm person, dissonant whispers, magic missile, ice knife

2nd level (3 slots): detect thoughts, hold person, mirror image, tasha's mind whip

3rd level (3 slots): animate dead, counterspell, dispel magic, fireball, hypnotic pattern lightning bolt, slow

4th level (3 slots): blight, dimension door, ice storm

5th level (3 slots): enervation, negative energy flood, scrying

6th level (1 slot): disintegrate, globe of invulnerability

7th level (1 slot): crown of stars, finger of death

8th level (1 slot): dominate monster, feeblemind

9th level (1 slot): gate, wish

Special Equipment. Crown of Corruption, Ring of Supreme Wizardry, a headband of intellect, a scroll of time stop, a scroll of prismatic wall, and two potions of supreme healing.

Sunlight Vulnerability. While in sunlight, Vlaakith has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight. She also has disadvantage on saving throws to avoid radiant damage.

Turn Resistance. Vlaakith has advantage on saving throws against any effect that turns undead.

Multiattack. Vaakith can use a spell of 1st level or lower. She then makes two attacks, only one of which can be a paralyzing touch attack.

Flying Silver Greatsword. Melee Spell Attack: +19 to hit, reach 30 ft., one target. Hit: 15 (2d6 + 9) slashing damage plus 21 (6d6) psychic damage. On a critical hit against a target in an astral body (as with the astral projection spell), the githyanki can cut the silvery cord that tethers the target to its material body, instead of dealing damage.

Paralyzing Touch. Melee Spell Attack: +14 to hit, reach 5 ft., one creature. Hit: 10 (3d6) cold damage. The target must succeed on a DC 22 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Parry. Vlaakith adds 5 to its AC against one melee attack that would hit it. To do so, she must see the attacker and be wielding a melee weapon.

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

Cantrip. Vlaakith casts a cantrip.

Teleport. Vlaakith magically teleports, along with any equipment she is wearing and carrying, to an unoccupied space it can see within 60 feet of it. She also becomes insubstantial until the end of her next turn. While insubstantial, she can move through other creatures and objects as if they were difficult terrain. If she ends its turn inside an object, she takes 16 (3d10) force damage and is moved to the nearest unoccupied
space.

Frightening Gaze (Costs 2 Actions). The lich fixes its gaze on one creature it can see within 10 feet of it. The target must succeed on a DC 22 Wisdom saving throw against this magic or become frightened for 1 minute. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to the lich's gaze for the next 24 hours.

Disrupt Life (Costs 3 Actions). Each non-undead creature within 20 feet of the lich must make a DC 22 Constitution saving throw against this magic, taking 21 (8d6) necrotic damage on a failed save, or half as much damage on a successful one.