No Pain No Gain

At the beginning of your second main phase exile
the bottom card of each opponents graveyard.
Ad {w}{u}{b}{r}{g}.
This mana can only be used to cast the just exiled
cards. You may play cards exiled this way until
end of turn. If you don't you take damage equal
to the CMC of the unplayed cards.
Put any unplayed cards at the bottom of their
owners library.