Visions of Phyrexia

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 {c}. This mana can’t be spent to cast a nonartifact spell.)