Consulta demoníaca

There is no way to make this card affect your opponent. It affects "you", and "you" means the controller of the spell. It has no targets.

You must name a card that actually exists in the game of Magic.

If you don't reveal the named card (perhaps because it was in the top six cards of your library), you'll end up exiling your entire library. You don't lose the game at that point, but will lose the next time you're instructed to draw a card.

You don't name a card until Demonic Consultation resolves.