Evigishki Merrowgeist

First Strike, Xyz Summon - As an additional cost
to cast this spell, sacrifice two creatures that each
have mana value 4. This creature enters the battlefield with two material counters on it.
Whenever Evigishki Merrowgeist deals combat
damage to a creature, if that creature would be
put into a graveyard this combat phase,
you may remove a material counter from Merrowgeist. If you do, shuffle that creature into
it's owners library.