The soul orb

{2}{w/b}{w/b}: Exile target creature an opponent
controls until The soul orb leaves the
battlefield. Then if 8 or more creatures are
exiled with The soul orb you win the game.
You may activate this ability only once each
turn.
scarcely ever found on any plane, its mystique
rivaling its potential. But only fool would try to
wield such power.