Special Equipment. Zanorath carries Tequtal. He wears a Robe of the Archmagi and has a The Shroud of the Void under his control.

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

Nullify the Inevitable. (Mythic Trait; Recharges after 10 days). If Zanorath is reduced to 0 hit points, he doesn’t die or fall unconscious. Instead, he draws from the energy stored In his phylactery and regains 200 hit points, and Triggers his Disrupt Life ability gaining temporary hp equal to the damage dealt. If Zanorath dies within 10 days of using this ability he must wait 3 weeks to be reformed by his Rejuvenation ability.

Rejuvenation. Zanorath’s body turns to dust when he drops to 0 hit points, and his equipment is left behind. Zanorath gains a new body after 3 days, regaining all his hit points and becoming active again. The new body appears within 5 feet of Zanorath’s phylactery, the location of which is hidden.

Mastery of Body and Soul. Zanorath's max hp cannot be reduced  has 6 ki points that can be used to take various actions.

Incarnate of Death. Zanorath's study of death allows him to extract vitality from another creature as it nears its demise. When he reduces a creature within 30 feet to 0 hit points, he gains 10 hp, he doesn’t gain this benefit for killing constructs or undead.

Spellcasting. Zanorath is a 20th-level spellcaster. His spellcasting ability is Intelligence (spell save DC 23, +15 to hit with spell attacks). Acererak has the following wizard spells prepared:

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

1st level (at will): ray of sickness, shield

2nd level (at will): arcane lock, knock

3rd level (at will): animate dead, counterspell

4th level (3 slots): blight, ice storm, phantasmal killer

5th level (3 slots): cloudkill, hold monster, wall of force

6th level (3 slots): chain lightning, eyebite, disintegrate

7th level (3 slots): finger of death, plane shift, teleport

8th level (2 slots): maze, mind blank

9th level (2 slots): power word kill, time stop

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

Paralyzing Touch. Melee Spell Attack: +8 to hit, reach 5 ft., one creature. Hit: 10 (3d6) cold damage, and the target must succeed on a DC 20 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.

Sunless Blade. Melee Spell Attack: +12 to hit, reach 5 ft., one target. Hit: 9 (3d6) force damage and 12 (4d6) necrotic damage, unless the living spell rolled an 19 or higher on the d20 for the attack, in which case the attack is a critical hit that deals 27 (9d6) force and 36 (12d6) damage instead. Any creature slain by this blade gains the sunlight sensitivity.

Invoke Curse. While holding the Tequtal, Zanorath expends 1 charge from it and targets one creature he can see within 60 feet of him. The target must succeed on a DC 23 Constitution saving throw or be cursed. Until the curse is ended, the target can’t regain hit points and has vulnerability to necrotic damage. Greater Restoration, remove curse or similar magic ends the curse on the target.

Presence of Death. Each creature of the Zanorath's choice that is within 120 feet of the Lich and aware of it must succeed on a DC 23 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the Lich's Presence of Death for the next 24 hours. While under this Frightened effect the creature cannot regain hit points.

Ki Touch (Costs 1 Ki point). Melee Spell Attack: +8 to hit, reach 5 ft., one creature. Hit: 10 (3d6) cold damage, and the target must succeed on a DC 20 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.

Hyperawareness (Costs 1 Ki point). Takes the Dodge action.

Etherial Movement (Costs 1 Ki point). takes the Dash or Disengage action.

Acererak 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. Acererak regains spent legendary actions at the start of his turn.

At-Will Spell. Acererak casts one of his at-will spells.

Melee Attack. Acererak uses Paralyzing Touch or makes one melee attack with his staff.

Focus of Death (Costs 2 Actions). Zanorath fixes his gaze on one creature he can see within 10 feet of him. The target must succeed on a DC 20 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 on it, the target is immune to Zanorath's gaze for the next 24 hours. While under this Frightened effect the creature cannot regain hit points.

Talisman of the Sphere (Costs 2 Actions). Zanorath uses his Shroud of the Void to move the Shroud of the Void under his control up to 90 feet.

Disrupt Life (Costs 3 Actions). Each creature within 20 feet of Acererak must make a DC 20 Constitution saving throw against this magic, taking 42 (12d6) necrotic damage on a failed save, or half as much damage on a successful one.

If Zanorath’s mythic trait is active, he can use the options below as legendary actions for 1 hour after using Nullify the Inevitable.

Focus the Body (Costs 3 Actions). Zanorath regains all Ki points