The Philosopher's Stone

{5}, {t}: Combine two creatures you control into
one creature; the new creature has all the abilities
of both creatures and a Power and Toughness
equal to the sum of the two creature's Power and Toughness stats. When the new creature or The Philosopher's Stone is destroyed, all cards go to
their owner's graveyards. The Philosopher's Stone cannot be untapped by any means until the
creatures leave play. Sacrifice a creature with converted mana cost =/> 5 to return Philosopher's
Stone from your