Beast of the Necropolis

Whenever a creature dies, put a +1/+1 counter
on Beast of the Necropolis.
When Beast of the Necropolis attacks, you may
remove any number of +1/+1 counters from it.
If you do, destroy target creature or artifact with
a mana cost equal to the number of counters
removed from Beast of the Necropolis.
Let the city of the dead crumble under the weight of
its own residents.