Akali Tethi, The Rogue Assassin

Assassinate. During her first turn, Akali has advantage on attack rolls against any creature that hasn't taken a turn. Any hit Akali scores against a surprised creature is a critical hit.

Evasion. If Akali is subjected to an effect that allows her to make a Dexterity saving throw to take only half damage, Akali instead takes no damage if she succeeds on the saving throw, and only half damage if she fails.

Cunning Action. Akali can take the Dash, Disengage, or Hide action as a bonus action.

Assassin's Mark. Once per turn, Akali deals an extra 24 (6d6) damage when she hits a target with a weapon attack.

Legendary Resistance (2/Long Rest). If Akali fails a saving throw, she can choose to succeed instead.

Multiattack. Akali makes two Kama or Shuriken Flip attacks.

Kama. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 10 (1d8 + 5) piercing damage, and the target must make a DC 16 Constitution saving throw, taking 28 (7d6) poison damage on a failed save, or half as much damage on a successful one.

Five Point Strike. Ranged Weapon Attack: +9 to hit, range 20/60 ft., up to five targets. Hit: 8 (1d4 + 5) piercing damage, and the target must make a DC 16 Constitution saving throw, taking 28 (7d6) poison damage on a failed save, or half as much damage on a successful one.

Shuriken Flip. Ranged Weapon Attack: +9 to hit, range 40/100 ft., one target. Hit: 9 (1d8 + 5) piercing damage. Akali can as a bonus action, for the next three turns, use ninjutsu to swap places with the shuriken once.

Twilight Shroud. Akali detonates a smoke bomb, creating a 20 ft. radius cylindrical shroud that expands over the next minute. The smoke can spread around corners. 

Entering the shroud renders Akali invisible. Akali's attacks and abilities will break the invisibility for one round.

Perfect Execution (Recharge 6). Akali attempts to execute a target below 50% health.

Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 10 (1d8 + 5) piercing damage, and the target must make a DC 17 Constitution saving throw or drop to 0 hit points.

Exemplary Ninja. Akali has 2 reactions per round.

Uncanny Dodge. When an attacker that Akali can see hits her with an attack, she can use her reaction to halve the attack’s damage.

Akali can take 2 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. Akali regains spent legendary actions at the start of her turn.

Strike. Akali makes one attack with her Kama.

Move. Akali moves up to half her speed without triggering opportunity attacks.

Swarm of Blades (Costs 2 Actions). Akali uses Five Point Strike.

Toxic Gas (Costs 2 Actions). Each creature within Akali's Twilight Shroud takes 20 (4d8) poison damage.