Sarcophagus

If Sarcophagus would untap with any charge
counters on it, remove a charge counter instead.
Then, if there are no charge counters left, return
each creature exiled with this to the battlefield
under its owner's control.
When Sarcophagus leaves, put each card exiled
with it into its owner's graveyard.
Whenever a creature you control would die, you
may tap Sarcophagus. If you do, exile that creature
and place 2 charge counters on Sarcophagus.