Parallax

When Parallax enters the battlefield, each player exiles the top 7 cards of his or her library.
Tap an untapped artifact or land you control: You get a credit counter. Any player may activate this ability.
Pay X credit counters: You may cast a spell with converted mana cost X exiled with Parallax without paying its mana cost. Any player may activate this ability, and only as a sorcery.