Ascended Vistar, the Undying

Legendary Resistance (5/Day). If the lich fails a saving throw, it can choose to succeed instead.

Rejuvenation. If it has a phylactery, a destroyed lich gains a new body in 1d10 days, regaining all its hit points and becoming active again. The new body appears within 5 feet of the phylactery.

Spellcasting. The lich is an 20th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 23, +12 to hit with spell attacks). The lich has the following wizard spells prepared:

Cantrips (at will): mage hand, prestidigitation, ray of frost

1st level (4 slots): detect magic, magic missile, shield, thunderwave

2nd level (3 slots): acid arrow, detect thoughts, invisibility, mirror image

3rd level (3 slots): animate dead, counterspell, dispel magic, fireball

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

5th level (3 slots): cloudkill, scrying

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

7th level (1 slot): finger of death, plane shift

8th level (1 slot): dominate monster, power word stun

9th level (1 slot): power word kill

Turn Immunity. The lich does not suffer any effect that turns undead.

Limited Magic Immunity: Venastar is immune to spells of 5th level or lower, unless he wishes to be affected. (This is similar to the rakshasa ability to resist any spell lower than 7th level.)

Discorporation: When Venastar drops to 0 hit points, he revives to half of his maximum hit points. If Venastar drops to 0 hit points again,  his avatar form is destroyed, but his essence travels back to his phylactery demiplane just beyond the Prime Material. He is unable to take physical form for an undisclosed time.

Paralyzing Touch. Melee Spell Attack: +12 to hit, reach 5 ft., one creature. Hit: 10 (3d6) cold damage. The target must succeed on a DC 18 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.

Penance Stare. As a bonus action Vistar can gaze into the soul of a creature and learn of all of their sins. These sins of the target manifest as a debilitating effect on the target. Roll 1d6 to determine that effect base on the following table.

Evil Eye. When Vistar  takes damage he can use his reaction to focus his Evil Eye on the creature that harmed him. When he does this, the targeted creature must make a constitution saving throw DC18, on a failure the target suffers 20 (6d6) necrotic damage. Half as much on a success.

The lich can take 5 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 lich regains spent legendary actions at the start of its turn.

Cantrip. The lich casts a cantrip.

1 – 5 Level Spells (Costs 2 Actions). The Lich casts a level 1 – 5 spell.

6 – 9 Level Spells (Costs 3 Actions). The Lich casts a level 6 – 9 spell.

Paralyzing Touch (Costs 2 Actions). The lich uses its Paralyzing Touch.

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 18 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 18 Constitution saving throw against this magic, taking 21 (6d6) necrotic damage on a failed save, or half as much damage on a successful one.