chaotic elemental

chaotic size size randomly changes roll 1d8 if 8 reroll. the higher the number the bigger the creature

chaotic skill: this creature has every skill at with a value of 1000

Spellcasting. The [chaotic elemental] is a 20-level spellcaster. Its spellcasting ability is [charisma] (spell save DC 500, +495 to hit with spell attacks). The [chaotic elemental] has following spells prepared:
all of the spells that exist in the game

but can only cast spells at random.

has 3 action a turn.

chaos bomb: cause explosion  range 1000000ft damage 1000000(50000d100 + 5000000)

 chaos sword: +500 to hit, reach 10 ft., 3 targets. Hit: 6000 (100d100 + 1000) [slashing] damage.

 chaos bow: +500 to hit, range 0/1000 ft., 5 targets. Hit: 6000 (100d100 + 1000) [piercing] damage.

can cast spells as bonus actions

chaotic reflection deal 100d100 to any attackers.

has 10 legendary actions

magical chaos (Costs 1 Actions): cause a wild magic surge that is 100 times more powerful than normal.

chaotic item (Costs 1 Actions): gain one random item

has 1 mythic actions

chaotic change (Costs 1 Actions) all enemies of this creature get a -100 to all ability scores permanently, while this creature and its allies gain +100 to all ability scores permanently