Akuma

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

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

Sneak Attack. Once per turn, the assassin deals an extra 14 (6d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of the assassin that isn't incapacitated and the assassin doesn't have disadvantage on the attack roll.

Greater invisibility Once per turn Akuma can cast greater invisibility on himself as long as he'd like, it can be disabled if it's hit (AC 25 HP 10) or if he's hit three times.

Danger Sense Advantage on Dexterity Saving Throws against Effects that he can see, such as traps and Spells. To gain this benefit, he can't be Blinded, Deafened, or Incapacitated.

Quick Reactions Akuma adds +6, and gets advantage to initiative 

Electric Shield This gives Akuma 40HP which is resistant to all physical attacks, once depleted it takes a short rest to recharge.

Multiattack. The assassin makes two attacks.

Mono-Katana. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 8 (3d6 + 5) slashing damage, and the target must make a DC 15 Constitution saving throw, taking 17 (5d6) necrotic damage on a failed save, or half as much damage on a successful one.

Throwing knives Ranged Weapon Attack: +10 to hit, range 20/60 ft., one target. Hit: 3 (1d4 + 5) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 17 (5d6) poison damage on a failed save, or half as much damage on a successful one.

Nunchaku Melee weapon attack: +6 to hit reach 5ft, one target., hit: 7 (2d6+5) bludgeoning damage, the target must make a DC 16 Constitution saving throw, being stunned till it's next turn on a failed save.

Barrel Kick Melee weapon attack: +10 to hit, reach 5ft, one target, hit:6 (2d8+5) bludgeoning damage, the target must make a DC 16 Strength or dexterity throw or be knocked prone and pushed back 10ft. On pass Target is only knocked back five feet

Restrain caster  Ranged weapon attack: +10 to hit, range 30ft, one target, hit: 6 (1d4+5) bludgeoning damage, the target must make a DC 20 Strength or Dexterity saving throw or be restrained and tethered to Akuma, the net as an AC of 10 and HP of 30.

Parry Akuma can increase his AC by +6 against one attack.

Cripple/disarm If an attack misses the attacker must make a DC 18 strength or dexterity save to either disarm (If a weapon is present) or cripple his opponent, making their next roll be reduced by 1d8, if it still hits damage is reduced by half.

Slow Fall  Akuma can use your reaction when he falls to reduce any falling damage he takes by an amount equal to 35.

Deflection Akuma can reduce one range attack, from any ranged weapon by 1d20+24, deflecting it back with his mono-katana. Dealing equal to an attack for a Mono-Katana (3d6+5 Without the necrotic damage) with a range of 20/60. This may also be used if a parry against a ranged attack failed.

Electric Discharge Akuma can decide to discharge his electrified shields to deal 2d10+10 lightning damage in a radius of 15 feet, on a failed DC15 Con save, passing reduces it by half. but destroying his electric shields. Though this disables Invisibility, and his shields need to recharge which takes a short rest.