The Trader

{2}: Reveal the top card of the "pile." You may
cast that spell without paying its mana costs. If
you don't, shuffle the "pile." Any player may
activate this ability. Activate only as a sorcery.
Sacrifice this creature: Return all cards from the
"pile" to their owners. They put those cards in
their graveyards. You can't sacrifice this creature
by any other means.