Phyrexian Scavenger

When Phyrexian Scavenger enters the battlefield
you may pay {1}. If you do, destroy target creature
an opponent controls, then put +1/+1 counters
on Phyrexian Scavenger equal to half the
destroyed creature's toughness, rounded up.
{1}{p/w}: {t}, Exile a card from a graveyard, if it was a creature card put +1/+1 counters on Phyrexian Scavenger equal to the exiled card's mana cost.
If the exiled card was a land, add one mana of
that colour.