The Leviathan

When The Leviathan deals combat damage to a
player exile target artifact player controls. For
each artifact exiled this way The Leviathan
gains a +1/+1 counter.
Remove a +1/+1 counter, {t}: Destroy target
creature.
The Leviathan doesn't untap during your
upkeep unless you exile 2 cards from
your graveyard.