Crimson Rogue

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

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

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

Lightfooted. The Rogue can take the Dash or Disengage action as a bonus action on each of its turns.

Multiattack. The Rogue makes two shortsword attacks.

Shortsword. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 5) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 24 (4d6) poison damage on a failed save, or half as much damage on a successful one.