Visions of Phyrexia - The Brothers' War (BRO)

At the beginning of your upkeep, exile the top card of your library. You may play that card this turn.
At the beginning of your end step, if you didn't play a card from exile this turn, create a tapped Powerstone token. (It's an artifact with "T: Add 1. This mana can't be spent to cast a nonartifact spell.")