Whenever Bioplasm attacks, exile the top card of your library. If it's a creature card, Bioplasm gets +X/+Y until end of turn, where X is the exiled creature card's power and Y is its toughness.
2/1/2014 The reminder text printed on Bioplasm is no longer correct. Abilities that define a creature’s power (and toughness) apply in every zone. The value of * is defined by such an ability.