Crypt Vampire

Rats you control are Food in addition to their
other types (They have "{2}, {t}: Sacrifice this
permanent: You gain 3 life.")
Sacrifice a creature: Crypt Vampire gets +1/+1
until end of turn. If the sacrificed creature's
power was 4 or greater, put a +1/+1 counter on
Crypt Vampire instead.
Exile a creature card from your graveyard: Create
a 1/1 black Rat creature token.