The Mind Stone

The Mind Stone does not count as a card in your
deck.
At the beginning of the game, exile The Mind
Stone from your library face down.
At the beginning of your end step, if you have 7
or more Instant and Sorcery cards in your
graveyard, put The Mind Stone face up onto the battlefield under your control.
{1}{t}: Sacrifice The Mind Stone: Gain control of
half of target opponent's creatures, rounded down.