Calamity, Master of Chaos

Legendary Resistance (2/Day). If Calamity fails a saving throw, it can choose to succeed instead.

Magic Resistance. Calamity has advantage on saving throws against spells and other magical effects that mention Intelligence or Charisma. 

Every Moment Counts. If Calamity has any remaining Legendary Actions at the start of their turn, they are added to any new Legendary Actions gained that turn. 

Aura of Entropy: The area within a 50ft radius of Calamity is considered difficult terrain, while a creature, besides Calamity, starts their turn the Aura of Entropy, they must flip a coin and call either Heads or Tails. If they call the coin flip correctly, they gain advantage on all rolls during their turn. If they call the coin flip incorrectly, they are pushed outside the Aura of Entropy, and cannot enter it during that turn. 

All-Seeing Eyes: Calamity's attacks do not consider resistances or immunities in damage calculation. 

Gambler's Saving Grace: Calamity may consume as many spell slots as they desire for this effect: roll a d20 and add your Proficiency Bonus (+6). If you roll lower or equal to the total spell slots consumed, Calamity returns to full health and is cured of all conditions as well as any effects from spells cast on it that would reduce its dice rolls or have it roll with disadvantage. 

Lady Luck: Any rolls on spells Calamity would cast that add any modifier other than Charisma are replaced with Charisma.

Spellcasting: Calamity is a 20th-level spellcaster. Its spellcasting ability is CHA (24 Save DC , +8 to hit with spell attacks). Calamity has following spells prepared, and may cast them without needing components:

Cantrips (at will): Mind Sliver, Vicious Mockery, Friends, Eldritch Blast

1st level (8 slots): Tasha's Hideous Laughter, Faerie Fire, Hex, Chromatic Orb, Charm Person

2nd level (8 slots): Mirror Image, Suggestion, Crown of Madness, Enlarge/Reduce, Shatter

3rd - 9th levels (3 slots each): None

Attack Action: Calamity may make a melee attack with its claws or wings on its turn.

Circular Spin Cycle: Calamity makes one melee weapon attack with its claws against any number of targets within its range. +7 to hit. Range: 5ft. Hit: 35 (2d12 + 29) slashing damage. Any creature hit by this attack must roll a DC 20 CON save or take an additional half the damage from Circular Spin Cycle as poison damage.

Rush of Flutters: Calamity makes an attack with its wings on one target in range. +12 to hit. Range: 10ft. Hit: 27 (6d4 +15) force damage. The target must roll against a DC 24 DEX save upon being hit. If they fail, they are pushed back 20ft and their movement speed is halved until the next round. 

Roll the Dice: If any creature within 50ft is in possession of a gaming set or deck of cards, Calamity channels the luck and strategy associated with their games against them. Each creature in range and meeting the conditions must roll a d20. Refer to the following table for its effects:

1-5: The creature cannot move until their next turn unless they are only wielding a gaming set or deck of cards. 

6-10: The creature gains vulnerability to psychic, force, and slashing damage until their next turn as long as they have moved towards Calamity during their previous turn. Otherwise they must take psychic damage equal to 1d6 times the number they rolled.

11-15: The creature may replace their movement speed on their next turn with 4d20. These dice cannot be rerolled or changed in any capacity. 

16-20: The creature teleports as if they had cast Misty Step as close to Calamity as their movement allows. 

Reactions: It may use a reaction to take an Attack Action. 

Calamity may take as many Legendary Actions per turn as the amount of creatures actively fighting it specifically at the start of each round.

Casting (1 Action): Calamity may cast any spell they have prepared. 

Patron's Summons (2 Actions): Calamity brings forth a Galwaja Replica Monster from across reality to an empty space of their choosing within 10ft of them. Any attacks that would be directed at Calamity must be directed at this creature instead. 

Puppeteer of Fate (3 Actions): Calamity must target a creature within 100ft radius of them before activating this ability. On its turn after the ability has been activated, the target must roll against a DC 30 INT Check. On a success, the effect does nothing. If it fails three times in a row, the target is reduced to 1 HP and is charmed or stunned until Calamity takes damage. 

Wave of Chaos (5+ Actions/1/Day): Calamity must use all of its Legendary Actions, totaling over five, to activate this ability. Each creature besides Calamity within 200ft of them must roll a DC 30 CON Save. If they fail, they take Necrotic and Force Damage equal to half of Calamity's HP and roll all skill checks with disadvantage until Calamity's next turn. If they succeed, they take a fourth of Calamity's HP in damage and gain no disadvantages.