Void Fissure: Zuerral starts it's turn within 30 feet of a 20x20 fissure. The height of the fissure increases with the size of the creatures that are summoned through it. When Zuerral is defeated the following occurs:

• All creatures within 50’ of the fissure must make a DC 27 STR save.
• On a failed save, the player takes 20d6 force damage, is pulled 10’ feet toward the fissure, and knocked prone. On a successful save, the creature takes half as much damage and is pulled 5' toward the fissure.
• Anyone who is within 5' the fissure after making the save will be sucked into the fissure and lost within the void.
• The fissure is then sealed shut.

Shadowed Form: Zuerral is immune to every single debuff, and cannot have its movement reduced by any means. It can also climb, swim, and navigate difficult terrain without issues.

Aura of Dominance: Zuerral has advantage on all saving throws, and every creature in a 60ft radius of Zuerral have disadvantage on all throws. In addition, every creature that can see Zuerral must make a DC 19 INT saving throw, or be Frightened for 1 minute. The Frightened creature can repeat the saving throw at the end of its turn, ending the effect early

Legendary Resistance (3/day): If Zuerral fails a saving throw, he may choose to succeed instead

Weapons Master: Zuerral has proficiency with every weapon he holds, and always has an arcane focus on hand

Amorphous: Zuerral can move through a space as narrow as 1 inch without having to squeeze

Spellcasting. Zuerral is a 20th-level spellcaster. Its spellcasting ability is +10 (spell save DC 20, +10 to hit with spell attacks). Zuerral has following Elemental spells prepared:

Cantrips (at will): Chill Touch, Infestation, Poison Spray, Ray of Frost, True Strike, Vicious Mockery
1st level (10 slots): Cause Fear, Command, Ray of Sickness,  Unseen Servant
2nd Level (10 slots): Crown of Madness, Moonbeam, Ray of Enfeeblement, Vortex Warp
3rd Level (9 slots): Conjure Barrage, Spirit Guardians, Summon Undead, Vampiric Touch
4th Level (9 slots): Confusion, Summon Construct, Summon Elemental, Ice Storm
5th Level (8 slots): Antilife Shell, Cone of Cold, Contagion, Insect Plague
6th Level (7 slots): Circle of Death, Disintegrate, Wall of Ice, Summon Fiend
7th Level (6 slots): Finger of Death, Power Word: Pain, Whirlwind, Forcecage
8th Level (6 slots): Abi-Dalzim's Horrid Wilting, Feeblemind, Power Word: Stun, Reality Break
9th Level (5 slots): Wish, Time Stop, Power Word: Kill, Ravenous Void

Abyssal Tendril: Zuerral lashes shadowy whips at a target in melee range. Deals 4d12+10 Slashing damage at a 10ft range, +10 to hit

Multiattack: Zuerral may use Abyssal Tendril up to three times.

Dimensional Shift: Zuerral may choose a target he can see, and the target and Zuerral must make a WIS Saving throw. If Zuerral succeeds, he swaps places with his target, if the target succeeds, this spell does nothing.

Regenerate Magic (2/day): Zuerral attempts to regain all of his magic, and must make a DC INT 21 save. If he succeeds, he gains all his magic spell slots back, failing has it do nothing

Shadows of Despair: Zuerral spews out a large conjuration of shadows and mist, every creature in a 100ft radius around him must make a DC 20 CON save, failing the throw has the affected be afflicted with Blindness, Deafness, and Exhaustion, along with 5d12+10 Poison and Necrotic damage. Succeeding the throw halves damage, and the target is not afflicted

Summon Undead: Zuerral may make a INT roll to summon a random Undead creature, the CR of said creature is determined by a D20. CR is equal to the roll (rolling a 6 gets you a CR 6 Undead.) The creature must be summoned within 5 ft of Zuerrals fissure.

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

Void Warp: Zuerral may teleport to half of its movement speed without provoking opportunity

Descent into Despair: Zuerral may make an Abyssal Tendril attack, or a Dimensional Shift action

Enter the description for how mythic actions work for your monster here.

Mythic Action Name (Costs # Actions). Enter the description for your mythic action.