Reality Shift is a uncommon Instant card from March of the Machine Commander (MOC), collector number 231. Current market price: $0.38, TCGplayer market prices via Scryfall.
Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)