Unexplainable Discovery

At the beginning of your upkeep, put the top
seven cards of your library into your graveyard.
If you would draw a card while your library has
no cards in it, you may pay 7 life instead. If you do, exile Unexplainable Discovery, then shuffle all cards from your graveyard into your library.
For the rest of the game, you may pay {0} rather than pay the mana cost for spells that you cast.