Psionic. Zyosho is a psionic being, which gives him notable perks, it allows him to add his Intelligence bonus to initiative rolls, granting him a +11 initiative bonus.

Special Equipment. Zyosho carries his double-bladed scythe, he has the Skull of Zyosho, an item that grants him more spells and such, he also has his magical skeleton.

Legendary Resistance (5/Day). If Zyosho fails a saving throw, he can choose to succeed instead.

Magic Resistance. Zyosho has advantage on saving throws against spells and other magical effects.

Regeneration. Zyosho regains 50 hit points at the start of his turn. If Zyosho takes damage from an artifact, this trait doesn’t function at the start of Zyosho's next turn. Zyosho dies only if he starts his turn with 0 hit points and doesn’t regenerate.

Undying. If Zyosho is slain, his soul refuses to accept its fate and lives on as a disembodied spirit that fashions a new body for itself after 1d100 years. Zyosho's soul can fashion a new body even if its old body was burned to ash or otherwise obliterated. When the new body is complete, Zyosho regains all his hit points and becomes active again. Zyosho's new body appears anywhere within 100 miles of where Zyosho was slain

Unusual Nature. Zyosho doesn’t require air, food, drink, or sleep.

Necrotic Carapace. When Zyosho is hit by a melee attack, the attacker takes 13 (3d8) necrotic damage.

Spellcasting. Zyosho is a 20th-level spellcaster. His spellcasting ability is Intelligence (spell save DC 24, +17 to hit with spell attacks). Zyosho has the following wizard spells prepared:
Cantrips (at will): mage hand, ray of frost, shocking grasp, zyosho's soul scythe
1st level (at will): ray of sickness, shield
2nd level (at will): arcane lock, knock
3rd level (at will): animate dead, counterspell, lightning bolt, fly, inflict wounds (3rd level)
4th level (3 slots): blight, ice storm, phantasmal killer
5th level (3 slots): cloudkill, hold monster, wall of force
6th level (3 slots): absolute zero, chain lightning, circle of death, disintegrate
7th level (3 slots): finger of death, plane shift, teleport, tether essence
8th level (3 slots): horrid wilting, maze, mind blank
9th level (3 slots): power word kill, time stop, ravenous void, meteor swarm

Multiattack. Zyosho uses Flight of the Damned (if available), Invoke Curse, or Spellcasting. He can then make one attack with his scythe.

Zyosho's Double-scythe. Melee Weapon Attack: +17 to hit, reach 5 ft., one target. Hit: 37 (4d12 + 11) necrotic damage, additionally, the target must succeed on a DC 16 Constitution Saving Throw or be reduced to 0 hit points.

Invoke Curse. While holding the Staff of Zyosho, Zyosho 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.

Flight of The Damned (Recharge 5-6). Zyosho conjures a torrent of flying, illusory entities that fill a 120-foot cone and passes through all creatures in that area before dissipating. Each creature in that area must make a DC 24 Intelligence saving throw. On a failed save, the creature takes 36 (8d8) psychic damage and is frightened of Zyosho for 1 minute. On a successful save, the creature takes half as much damage and isn't frightened. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. A creature that can see through illusions is immune to this feature.

Vile Teleport. Zyosho teleports, along with any equipment he is wearing or carrying, up to 30 feet to an unoccupied space he can see. He can cause each creature of his choice within 15 feet of his destination space to take 10 (3d6) necrotic damage. For each creature that takes this damage, Zyosho regains 10 hit points.

Counterspell. Zyosho casts Counterspell. Ths caster takes 10 (3d6) psychic damage if the spell fails.

Fell Rebuke. In response to being hit by an attack, Zyosho conjures a shield of necrotic energy, gaining a +5 bonus to AC until the start of his next turn (including against the triggering attack). While he has this shield, any creature that misses on a melee attack against Zyosho takes 10 (3d6) necrotic damage and must succeed on a DC 24 Constitution saving throw or have disadvantage on attack rolls, ability checks, and saving throws using Strength or Dexterity until the end of its next turn.

Zyosho can take 5 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. Zyosho regains spent legendary actions at the start of his turn.

Scythe. Zyosho attacks using his scythe.

Vile Teleport. Zyosho uses his Vile Teleport bonus action.

Spellcasting (Costs 2 Actions). Zyosho casts an at will spell.

Disrupt Life (Costs 3 Actions). Each creature within 20 feet of Zyosho 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.