Rotburrow Wurm

Flash, Flying
{1}, Exile a creature card from your graveyard: Rotburrow Wurm loses flying and gains trample until end of turn. Put a +1/+1 counter on it. Only an opponent may activate this ability.
Feed it, and it will fall to the earth, ravenous for decaying flesh. But soon it will be sated and on high it will fly, eagerly awaiting its next meal.