Aspect of the Dungeon Master

Regeneration. Aspect of the DM regains 47 (2d10+36) hit points each round, or double that if it has used Godlike Rejuvenation in the past hour.

Godlike Rejuvenation. Once per day, when Aspect of the DM drops to 0 hit points, he may choose regain 1000 hit points. In the following hour, his Legendary Actions go from 5 to 8 and he can use a Mythic Action as a Legendary Action. At the end of the hour, his number of Legendary actions drops to 5 again, and he can no longer use attacks from the Mythic Actions section. If Aspect of the DM dies, he instantly reforms in his lair in the Infinite Staircase

Spellweaving. The Aspect of the DM is a 20th-level spellcaster. His spellcasting ability is Charisma (spell save DC 27, +19 to hit with spell attacks). The Aspect of the DM can cast any spell from any spell list without needing to learn or prepare it.  The Aspect of the DM can also cast a spell multiple times with an action. If it is a cantrip, he can cast it up to 4 times, up to 3 times for a spell of 1st-4th level, and up to 2 times for a spell of 5th-8th level.

Spell Resistance. The Aspect of the DM can choose not to be affected by spells of 8th level or lower.

Xvart/Svirfneblin Transformation. As a Bonus Action, the Aspect of the DM designates one creature within 500ft. That creature must make a DC 40 constitution saving throw or be turned into a Xvart or Svirfneblin (Aspect of the DM's choice). The creature has advantage if it hates K-Pop, or disadvantage if it likes it. If a creature likes Blackpink, the save automatically fails.

Multiattack. Aspect of the DM makes 5 Greatsword attacks attacks.

Greatsword. Melee Weapon Attack: +17 to hit, reach 10 ft., 1 target. Hit: 32 (2d8 + 20) [slashing] damage plus 22 (2d12 + 9) [radiant] damage. 

DM Snap. The Aspect of the DM picks up to 10 creatures within 500ft. Each must make a DC 50 Constitution saving throw or be instantly killed. They cannot reform in any way, even if they have a Lich's Rejuvenation or a God's Discorporation or similar magic. No amount of magic can revive them. If they make the save, they get reduced to one hit point, any immunity to Exhaustion is removed for 24 hours, and they gain 5 levels of exhaustion. They then  cannot heal in the next 24 hours.

Redirection. When a creature misses an attack against the Aspect of the DM, he can choose to redirect the would-be damage to the creature who would have dealt it.

The Aspect of the DM can take 5 legendary actions, choosing from the options below. Up to two legendary action option can be used at a time and only at the end of another creature’s turn. The Aspect of the DM regains spent legendary actions at the start of its turn. The amount of legendary actions becomes 8 if he has used Godlike Rejuvenation in the past hour.

Cast Spell. The Aspect of the DM casts a spell of up to 2nd level of his choice.

Planar Gate. (Costs 2 Actions) The Aspect of the DM creates a planar gate and summons up to 5 creatures with a combined Challenge Rating of up to 10 as allies.

If the Aspect of the DM has used Godlike Rejuvenation in the past hour, he can use a mythic action as a Legendary action.

Lesser DM Snap (Costs 3 Actions). The Aspect of the DM picks up to 5 creatures within 200ft. Each must make a DC 40 Constitution saving throw or be instantly killed. They cannot reform in any way, even if they have a Lich's Rejuvenation or a God's Discorporation or similar magic. No amount of magic can revive them. If they make the save, they get reduced to 5 hit points, any immunity to Exhaustion is removed for 24 hours, and they gain 4 levels of exhaustion.