Auril assassin

Freezing Weapon Attack. Once per turn, the Auril assassin covers their weapon in a layer of ice and stabs a creature with it. On a hit, the target takes the original weapon damage and 2d6 cold damage. Hit or miss, the layer of ice then explodes. The target and each creature within 5 feet must succeed on a Dexterity saving throw or take 2d6 cold damage.

Cold Blood. During its first turn, the Auril assassin has advantage on attack rolls against any creature that hasn't attacked him yet. Any hit the assassin scores against any of these creatures is a critical hit.

Special Training. Since their goddess is the goddess of the winter, they are trained to embrace the cold, making them immune to cold damage.

Multiattack. The assassin makes two shortsword attacks.

Shortsword. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 24 (7d6) cold damage on a failed save, or half as much damage on a successful one.

Light Crossbow. Ranged Weapon Attack: +6 to hit, range 80/320 ft., one target. Hit: 7 (1d8 + 3) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 24 (7d6) colddamage on a failed save, or half as much damage on a successful one.