Biograft

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

Sneak Attack. Once per turn, the Biograft 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 Biograft that isn't incapacitated and the assassin doesn't have disadvantage on the attack roll.

Multiattack. The Biograft makes two Sai attacks.

Mechanized Sai. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 15 (3d8 + 3) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 15 (5d6) radiant damage on a failed save, or half as much damage on a successful one.

Slash Storm. Ranged Weapon Attack: +6 to hit, range 80/320 ft., one target. Hit: 14 (2d10 + 4) slashing damage, and the target must make a DC 17 Constitution saving throw, taking 24 (5d6) radiant damage on a failed save, or half as much damage on a successful one.

Echo Execution. Ranged Weapon Attack: The Biograft teleports to the space 5 feet in any direction from one target within 120 feet of it, and the target must make a DC 18 Dexterity saving throw, taking 24 (5d6) radiant damage on a failed save, or half as much damage on a successful one.

Overdrive. Effect: Once enabled, the Biograft has advantage on all attack rolls, ability checks, and saving throws. Any hit with a roll above 18 the assassin scores is a critical hit. The Biograft takes 15 damage at the beginning of initiative order each round. Overdrive can be disabled at the cost of the Biograft's movement that turn.