Sinh, the Slumbering Dragon

Flying, vigilance, haste
Whenever Sinh, the Slumbering Dragon attacks,
look at the top seven cards of your library. You
may cast an instant or sorcery spell with mana
value less than or equal to Sinh, the Slumbering
Dragon's power from among them without
paying its mana cost. Put the rest on the bottom
of your library in a random order.