Akt

Assassinate. During its first turn, the assassin has 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, Akt deals an extra 14 (4d6) 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, and is stealthing and the assassin doesn't have disadvantage on the attack roll.

Shapeshift. The changeling can turn themselves into anyone else at will. The only way to tell the difference would be a Insight Check or a DC 18 Perception Check. 

Mark of Shadows. Akt can put a mysterious mark on any humanoid. The mark lasts for 24 hours and can be removed with dispel magic. Akt knows the location of any target with the mark and has advantage against all attack rolls against them. The mark is a runic symbol made of shadows on the target's chest. He can mark up to two people at a time. The Mark is a free action, but he can only mark one person per turn. 

Shadow Weapon. Akt takes a bonus action to summon his weapon. The weapon is considered a magic +1 weapon and can take any form. Akt instantly has proficiency with it. If Akt's shadow weapon is a shield, he can resist the attacks of anyone with the mark of shadows on them.

 Deft Movement. Akt can stealth, dash, or disengage as a bonus action. 

Longsword. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 6 (1d10 + 5) piercing damage, and the target must make a DC 14 Constitution saving throw, making it impossible to cast spells, use Ki points, or any other ability that has limited uses per day next turn on a failed save.

Light Crossbow. Ranged Weapon Attack: +7 to hit, range 80/320 ft., one target. Hit: 7 (1d8 + 7) piercing damage, and the target must make a DC 14 Constitution saving throw, making it impossible to cast spells, use Ki points, or any other ability that has limited uses per day next turn on a failed save.

Akt can use his reaction to cover himself in shadows, giving him 10 TEMP HP till his turn. He can do this three times per day.