Cataclysm

Legendary Resistance (10/Minutes). If the Cataclysm fails a saving throw, it can choose to succeed instead.

Destructive Resistance. The Cataclysm has an advantage on all rolls. If it succeeds a saving throw It will deal 6d4+4 piercing damage to all targets within 30 ft.

Unbreakable Smoke. Once a turn the Cataclysm can choose to receive no damage from an attack. Will always negate damage if the damage is  above the Cataclysm's max health, and negate anything that would instantly kill it.

Siege Monster. The Cataclysm deals Triple damage to objects and structures.

Burning Heart. When below 600 hp the Cataclysm will do 3d6 fire damage to all targets within 75 ft every turn.

Flight. The Cataclysm can fly at will in any direction.

Perfect Will. Cataclysm can do up to 4 actions on its turn.

Divine concentration. The Cataclysm can concentrate on up to ninety spells at once. It cannot fail a concentration check

Divine Nature. The Cataclysm doesn't need to eat, drink, sleep or breathe to survive and it's immune to any effects that alter it's form, and it won't age and is immune to any effects that alter it's age.

Astral Core. The Cataclysm's ability scores are multiplied by 6600. Additionally the Cataclysm rewards those who manage to kill it with 277,998,660,000,000,000 XP, 822770000 platinum, and 80 magic items (items chosen by DM)

Copy. Any action the Cataclysm observes will be added to it's action list, and any items or components needed will be materialized from within the Cataclysm.

Apotheosis. Upon death the Cataclysm will let out a blast of smoke, dealing 8d20 force damage to all within 8000 ft. Afterwards, the Cataclysm will be revived with new actions, doubled damage, but half of it's max hit points. When this trait activates a second time all actions made by the Cataclysm that target creatures have the max amount of targets doubled. This trait can only take effect twice, leading to half health then quarter health, and double then quadruple damage.

Singularity Supernova. This effect triggers when Apotheosis can no longer trigger. The Cataclysm will begin to implode and beams of energy will come out of it. All within 4000 ft. must succeed a DC 22 dexterity saving throw or take 22d10 radiant damage and 32d12 piercing damage. The Cataclysm will also start to pull everything in an 8000 ft. radius into it, and all within 80000 ft. must succeed a DC 29 dexterity saving throw or be instantly killed no matter what, and all within 2000 ft. will automatically be sucked in no matter what. Afterwards, the Cataclysm will explode, and everything within 98700000000000000000000000000000000000000000 multiplied by 2220000 ft.  will take 8822400000d100 damage, multiplied by 2220000000000000. There is no way to avoid the damage caused by this trait, and will kill those above 

Bite. Melee Weapon Attack: +18 to hit. reach 35 ft. 1 target Hit:  8d20+18 bludgeoning damage plus 3d10 acid damage plus 2d10 fire damage plus 2d10 cold damage

Claw. Melee Weapon Attack:  +16 to hit reach. 20 ft. 1 target. Hit:  6d12+16 bludgeoning damage plus 1d10 piercing damage plus 2d12 slashing damage

Frightful Presence. Each creature of the Cataclysm choice within 290 ft. of it and aware of it must succeed on a DC 18 Wisdom saving throw or become frightened  for 32 minute. A creature can repeat the saving throw at the end of each of its turns, with disadvantage if the Cataclysm is within line of sight, 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 Cataclysm Frightful Presence for the next hour.

Consume. The Cataclysm makes one bite attack against a Large or smaller creature within 20 ft. If the attack hits, the target takes the bite’s damage, the target is swallowed. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the Cataclysm, and it takes 22d20 fire damage plus 12d12 acid damage at the end of each turn

If the Cataclysm takes 100 damage or more on a single turn from a creature inside it, the Cataclysm must succeed on a DC 16 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the Cataclysm. If the Cataclysm dies, a swallowed creature is no longer incapacitated by it and can escape from the corpse by using 30 feet of movement, exiting prone.

Collapsion Beam. Ranged Weapon Attack:  +12 to hit reach 80 ft. 1 target. Hit:  9d10+16 radiant damage.

Teleport. The Cataclysm instantly teleports to any location it has been.

Control. The Cataclysm will attempt to control up to 10 creatures within 300ft. These creatures must make a DC 20 wisdom saving throw. If failed, All decisions and actions made by the creature(s) are now controlled by the Cataclysm. Each turn the creature can re-attempt to succeed the saving throw, and when they succeed, the Cataclysm loses control of them, and the creature is immune to this action for 3 turns.

Arcane Knowledge. The Cataclysm is able to cast any magic spell. It has endless spell slots and does not need any components to cast. It's spell slot are regained every 4 hours.

Planar shift. The Cataclysm will teleport to any location within another plane.

Crisis. The Cataclysm will materialize a 50 ft. radius of black ooze. Anything that comes in contact with this ooze must succeed a DC 22 dexterity saving throw, or take 8d20 acid damage. This action is only usable after Apotheosis triggers at least once.

Summon. The Cataclysm will instantly create any creature it knows of. This action is only usable after Apotheosis triggers at least once.

Disable. The Cataclysm will target one creature. This creature must succeed a DC 19 wisdom saving throw, or become unable to take any actions for 3 turns. This action is only usable after Apotheosis triggers twice.

Crumble. The Cataclysm will target a 40 ft. by 40 ft. area, dealing 16d8 bludgeoning damage to all within that area, and for the rest of the Cataclysm's life, all creatures who enter that area will take 10d10 acid damage. This action is only usable after Apotheosis triggers twice.

Destruction. Cataclysm send out a wave of force in every direction. The wave is 40 ft. tall and reaches 200 ft. all targets within that range must succeed a DC 23 dexterity saving throw, or take 5d20+2 physic damage plus 4d20+10 force damage.

Flames of Darkness. If the Cataclysm takes 65 damage in a single turn, It can use this action. all targets within 100 ft. must succeed a DC 20 Constitution saving throw, or take 180 fire damage plus 50 force damage.

Ward of Souls. If the Cataclysm takes 100 damage in a single turn, it will instantly use this action. It creates a sphere with a 500 ft. radius where no magic can function. Creating a new sphere removes the past one.

Delay. If any creature within 190000 ft. of the Cataclysm take more than 6 actions, the Cataclysm will instantly use this action. All creature within 180 ft. will take 8800 psychic damage. all creature within 190000 ft. will be unable to do any action for 30 minutes. This action is only usable after Apotheosis triggers at least once.

The Cataclysm can take 10 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. The Cataclysm regains spent legendary actions at the start of its turn.

Move. The Cataclysm moves up to triple its speed.

Determination. The Cataclysm triples all damage dealt for the next turn.

Will. The Cataclysm will instantly use one of its actions. This action is only usable after Apotheosis triggers at least once.

The Cataclysm can take 5 mythic actions, choosing from the options below. Only one mythic action option can be used at a time and only at the end of another creature’s turn. The Cataclysm regains spent mythic actions at the start of its turn.

Annihilation. The Cataclysm choses one target or an area anywhere. The area can be any shape and size. On the next turn, the target or area will instantly be removed from reality. This includes souls and other non physical targets or areas. This attack negates any immunity of any kind, along with negating any method of negating the damage.

Decahedron. Using it's 12 arms, the Cataclysm divides up to 12 claw attacks between up to 12 targets.

Growth. The Cataclysm grows up to 7777888888000000000000 times it's original size, multiplying all damage by 99778886666660000000000000000000. multiplies current health by 999990000000000000000000. It's armor class increases to 9900, and all of it's stat scores increase to 899900000. last 3 turns.

Absolute. The Cataclysm targets up to 90 creatures within 55000 ft. Each target will take 3d8 damage every hour, and anyone they touch will begin to be effected by this too. After 5 days, the those effected by this will instantly die, no matter what.