9th-level / Stone Dragon
You slam into your foe, turning bones into dust and muscle into bloody pulp. Your foe's body is left a crippled, twisted mockery. Your attack causes damage to the structure of your foe's body. As part of this maneuver, you make a single melee attack. On a hit you deal damage as normal aswell as reducing the target Constitution score by 3d6, if the target Constitution score falls to or below zero they die instantly as they turn to a pile of flesh and bone. The targets maximum hit points reduce as expected with the new Constitution score. The damage to the targets ability score can be recovered by 1d6 whenevery they finish a long rest.