Volmar, the gravedigger

+2: Look at the top card of any library. You may pay X to exile that card, where X is the number of cards exiled this way.
-1: At the begining of your next upkeep, add X to your manapool where X is the number of cards exiled by Volmar, the gravedigger.
-10: For the rest of the game, you may cast cards from exile without paying their mana cost.