Aquatic. The Vhushk is able to breathe both air and water.

Rejuvenation. When the Vhushk's body is destroyed, its soul lingers. After 24 hours, the soul inhabits and animates another humanoid corpse within a body of water on the same plane of existence and regains all its hit points. While the soul is bodiless, a wish spell can be used to force the soul to go to the elemental plane of water and not return.

Turn Immunity. The Vhushk is immune to effects that turn undead.

Vengeful Tracker. The Vhushk knows the distance to and direction of any creature against which it seeks revenge, even if the creature and the Vhushk are on different planes of existence. If the creature being tracked by the Vhushk dies, the Vhushk knows.

Multiattack. You may make two longsword attacks.

Longsword. Melee Weapon Attack: +4 to hit, reach 5 ft., 1 target. Hit: 5 (1d6 + 2) [slashing] damage. 

Flintlock. Ranged Weapon Attack: +4 to hit, range 60/320 ft., 1 target. Hit: 7 (1d10 + 2) [piercing] damage. Requires an action to reload.

Final Stand. The Vhushk may decide to drop it's weapon and make an attack using the full force of it's body. When it does this, it receives half of the damage of the roll as force damage. It can only make this attack when below 1/4 health. Melee Weapon Attack: +7 to hit, reach 5 ft., 1 target. Hit:  14 (3d6 +4) [bludgeoning] damage.

Retaliatory Glare (1/long rest). The target makes a DC 13 wisdom saving throw. On a failed save, the target takes 5d4 necrotic damage, and has disadvantage on all rolls until the end of your next turn.