Ghastly Demise

Destroy target nonblack creature if its toughness
is less than or equal to the number of cards in
your graveyard.
"The asylum stood silent, abandoned, forgotten. Yet something lingered within its frozen walls, something
cold and dark. A presence moved, unseen but felt,
stalking the corridors. It sought its prey, drawn to
the weak and broken. None who encountered
the ghastly demise within those walls ever emerged
alive."