Sarulf, Realm Eater

Whenever a permanent an opponent controls
is put into a graveyard from the battlefield,
put a +1/+1 counter on Sarulf, Realm Eater.

At the beginning of your upkeep, if Sarulf has
one or more +1/+1 counters on it, you may
remove all of them. If you do, exile each other nonland permanent with mana value
less than or equal to the number of counters removed this way.