At the beginning of your end step, you may sacrifice a creature. If you do, look at the top X cards of your library, when X is that creature's mana value. You may put a creature card from among them onto the battlefield. Put the rest on the bottom of your library in a random order.
Near Mint - $3.00
Lightly Played - $2.75
Moderately Played - $2.50
Heavily Played - $1.75
Damaged - $1.50
Near Mint Non-English - $3.00
Lightly Played Non-English - $2.75
Moderately Played Non-English - $2.50
Heavily Played Non-English - $1.75
Damaged Non-English - $1.50