Whenever you cast your first spell during each of your turns, exile the top card of target opponent's library and create a Treasure token (A Treasure is an artifact with ", Sacrifice this artifact: Add one mana of any color."). Then you may cast the exiled card without paying its mana cost if it's a spell with mana value less than the number of artifacts you control. If you don't cast it this way, you may cast it this turn.