River's Journal [Codie]

You can't cast permanent spells.
{4}, {t}: Add {w}{u}{b}{r}{g}. When you cast your
next spell this turn, exile cards from the top of
your library until you exile an instant or sorcery
card with lesser mana value. Until end of turn,
you may cast that card without paying its mana
cost. Put each other card exiled this way on the
bottom of your library in a random order.