Callisto, Corporist Maestro

Legendary Resistance (3/Day). If Callisto fails a saving throw, he can choose to succeed instead. 

Magnum Opus: Tibia. Whenever Callisto makes an attack, he gains 4 Charge. He can have up to 20 Charge. His attacks are considered magical for the purposes of overcoming resistances and immunities, and can make one reaction per turn. 

Outmoded Art. Whenever Callisto takes 20 or more damage on a turn (factored after resistances), he loses 1 Charge for every 20 damage that he took. 

Transcend the Corpus (1/Short or Long Rest). Once Callisto is at 138 or less hit points, he interrupts the turn and uses Closing Time Installation Art no. 1. And then, his hit points reset to 221 and he gains the Artwork Pleasing to the Senses and Healthy Corpus Leads to Healthy Ingredient features. 

Please Stop Running and Be Seated. Whenever Callisto damages a creature, that creatures loses 5 movement speed until the end of its next turn, stacking up to 15 feet reduction. Additionally, affected creatures must make a DC 20 Strength saving throw or subtract 1d6 from their damage rolls on their next turn, stacking up to 3d6. 

Corpus-Centric Art. Whenever a creature within 30 feet fails a saving throw, Callisto gains an extra 1d6 slashing damage on his attacks during his next turn (up to 3d6 per attack). 

Artwork Pleasing to the Senses (Requires Transcend the Corpus). Whenever Callisto or Albina are within 60 feet of each other, and one of them uses an action or legendary action that either needs to recharge or spends 3 legendary actions, they both gain +2 to attack and damage rolls and AC until the end of their next turns. 

Healthy Corpus Leads to Healthy Ingredients (Requires Transcend the Corpus). Callisto prioritizes attacking the highest level or CR creature within sight. His attacks against this creature deal an extra 2d6 slashing damage.

Multiattack. Callisto uses Uncanny Valley and makes three different attacks using Tibia.

Uncanny Valley. Each creature of Callisto's choice that is within 120 feet of him and aware of him succeed on a DC 20 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, 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 Callisto's Uncanny Valley for the next 24 hours.

Tibia - Anatomize. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 3d6 + 7 slashing damage. Spend 2 Charge to inflict an additional 2d6 necrotic damage. 

Tibia - Gather Ingredient. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 2d10 + 7 slashing damage. Spend 3 Charge to inflict a DC 20 Constitution saving throw, where on a failure the creature's attack rolls on their next turn are made at disadvantage. 

Tibia - Improvised Ribcage. Ranged Weapon Attack: +13 to hit, range 30/90 ft. one target. Hit: 3d6 + 7 piercing damage. The target then must make a DC 20 Strength saving throw, or take 2d6 psychic damage and be pulled towards Callisto for 60 feet. On a success, the target takes half damage and is not pulled towards him.  

Tibia - Overcharge. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 3d8 + 7 force damage. Spend 2 Charge to inflict an additional 1d6 force damage, up to a maximum of spending 8 Charge and an additional 4d6 force damage. 

Tibia - Volatile Isolation. Callisto chooses up to three creatures within 60 feet of him. He spends 4 Charge for each, and forces them to make DC 20 Charisma saving throws. Creatures that fail the saving throw are transported to a portion of the Labyrinth under his control for one round. He may choose to follow them into the Labyrinth before returning with them at the end of his next turn.

Tibia's Melody - Anatomization of the Unanatomized by the Anatomized (Costs 10 Charge, Recharge 4 - 6). Creatures in a 60 foot cone must make a DC 20 Strength saving throw as fleshy, bleeding bone structures erupt from the area. Creatures who fail the save take 3d8 piercing damage and 3d8 necrotic damage, and half as much on a success. Affected creatures then have their movement speed reduced by 10 feet, and Callisto gains temporary hit points equal to half the total damage dealt. Callisto can spend a continuous amount of Charge to add 1d8 to either piercing or necrotic damage, each die costing 1 Charge, up to a maximum of an additional 4d8 for either damage type. 

Deploy Barrier. Callisto can spend between 2 to 7 Charge and gain temporary hit points equal to twice the Charge spent. 

Allow Me to Briefly Enjoy My Pupil's Exhibition (1/Round). If Albina is present and is about to be attacked, and the attacker is within 90 feet, Callisto may take a reaction to spend 5 Charge to instantly teleport between Albina and her attacker and make an attack roll against the incoming attack. If his attack roll is higher than the incoming attack, the attack is canceled and if the attacker is within 10 feet, it takes damage equal to his attack. 

Vandalism is Prohibited (2/Round). Upon being targeted by an attack, Callisto can make a melee attack against it as a reaction. If this attack rolls higher than the incoming attack roll, the attack is canceled. If the attacker is within 5 feet of Callisto, they also take half of his attack's damage roll.

Callisto has four legendary actions, which he can use at the end of another creature's turn. He regains all spent uses at the start of his turn. 

"Welcome to my parlor." (Costs 2 Actions) Callisto uses Tibia - Volatile Isolation. 

Curation of the Exhibits. Callisto moves up to his movement speed without provoking attacks of opportunity. 

"Direct any concerns to me!" Callisto makes an attack using Tibia - Anatomize or Tibia - Gather Ingredient. 

"Shall we explore deeper?" Callisto uses Tibia - Improvised Ribcage. 

If Callisto's Transcend the Corpus has been used, he can use the options below as legendary actions for 1 hour. 

Closing Time Installation no. 1 (Costs 3 Actions). Creatures within 60 feet of Callisto must make a DC 20 Constitution saving throw or be restrained for one minute. Creatures restrained this way take 1d6 piercing damage at the start of their turns, and can use their action to destroy the restraints (30 HP, 12 AC) to end the condition early.