Architect K

Step of the regretful. Whenever Architect K moves, he can choose to make that movement instantaneous. Additionally, Architect K's jump distance is doubled.

Overflowing sadness. Architect K can choose to make the ground within up to 15 ft. of him difficult terrain.

Terminal velocity blow. If architect K moves at least 30 ft. instantaneously before immediately using a finisher, on a hit the finisher deals an additional 11 (2d10)  bludgeoning damage.

Evasion. When Architect K is subjected to an effect that allows him to make a Dexterity saving throw to take only half damage, he instead takes no damage if he succeeds on the saving throw, and only half damage if he fails.

Combo Finisher (3/Day). After finishing a multiattack with a Haymaker finisher, Architect Muki can teleport to the creature hit by it, and then make one additional finisher attack that isn't Haymaker.

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

Multiattack. Architect K makes three unarmed strikes, and then uses a finisher.

Haymaker finisher. Melee Weapon Attack: +19 to hit, reach 5 ft., 1 target. Hit: 22 (2d10 + 10) bludgeoning damage and 16 (2d10 + 5) psychic damage. If the target was a creature, it is launched 30 ft. away from Architect K.

Heel-Kick finisher. Melee Weapon Attack: +19 to hit, reach 5 ft., 1 target. Hit: 32 (4d10 + 10) bludgeoning damage. If the target was a creature, it must make a DC 27 Strength saving throw. On a fail, they are knocked prone.

Uppercut finisher. Melee Weapon Attack: +19 to hit, reach 5 ft., 1 target. Hit: 22 (2d10 + 10) bludgeoning damage and 10 (1d10 + 5) psychic damage. If the target was a creature, it is launched 30 ft. upwards.

Unarmed Strike. Melee Weapon Attack: +19 to hit, reach 5 ft., 1 target. Hit: 21 (2d10 + 10) bludgeoning damage. 

Architect K can dash, dodge, hide, or disengage as a bonus action.

Scatter (recharge 5-6). When Architect K is hit with a melee attack, he can use his reaction to teleport to any space within 30 ft. of him, and the hit becomes a miss.

Counter (5-6). When a creature misses Architect K with a melee attack, he can use his reaction to make a finisher attack against the creature.

Architect K can take 3 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. Architect K regains spent legendary actions at the start of its turn.

Vanish . Architect K makes a dexterity (stealth) check.

Desynchronize (Costs 2 Actions). Architect K makes an unarmed strike against a creature. If it hits, the creature must make a DC 27 Constitution saving throw. On a failed save, the creature has disadvantage on all attack rolls, ability checks, and saving throws until the start of its next turn.

Right behind you (Costs 2 Actions). Architect K teleports behind a creature within 30 ft. of him. The creature must make a DC 27 wisdom saving throw. On a failed save, Architect K makes a finisher attack. On a successful save, he makes an unarmed strike with disadvantage.

Once per week, when architect K reaches 0 hit points, he regains 150 hit points. For one hour, his movement speed increases by 60 ft., he inflicts the maximum possible damage with each of his attacks, and is immune to effects that would instantly kill him, such as spells like power word kill. Additionally, he gains 12 mythic actions, which he can expend to use the following actions on his turn. If he runs out of mythic actions, he cannot regain more until this effect is triggered again.

Pure, unfiltered sorrow (Costs all remaining actions, min 4). Architect K lets out every last ounce of pain and suffering in his soul, letting it wreak havoc on his surroundings. Each creature within a 30 ft. radius of him must make a DC 27 Constitution saving throw. On a failed save, a creature takes 140 (40d6) psychic damage, or half as much on a success.

Misery Cannon (Costs 3 actions). Architect K unleashes immense amount of regretful energy, focusing it into a lethal beam. Each creature in a 120 ft. line must make a DC 27 Dexterity saving throw. On a failed save, a creature takes 33 (6d10) force damage and 33 (6d10) psychic damage, or half as much on a success.