Undead Fortitude. If the creature is reduced to zero hit points without the head being targeted, it is brought back to 1 hit point. 
If legs are targeted when the creature is brought to zero hit points, it's movement speed is reduced to one, and it is knocked prone
If it's torso is targeted, then the creature is stunned on its next turn.
If it's arms are targeted, then it has disadvantage on all attack rolls.

Slash: Melee Weapon Attack:  Deals 1d8 points of slashing damage. Target must make a DC10 constitution save. On a fail, creature deals 1d10 virus damage to targets mental health. +2 to attack roll
Bite: Melee Weapon Attack: Deals 1d6 points of piercing damage. Target must make a dexterity save (DC12). On a fail, the creature if thrown into a blind madness and attacks any creature in range.