Archmagos Belisarius Cawl

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 the end of turn, you
may cast that card without paying its mana cost.
Put each other card exiled this way in the bottom
of your library in a random order.