Door to Infinity

You may cast cards exiled by Door to Infinity.
{t}: Exile the top card of each library.
{5},{t}: Exile the top 7 cards of target opponent's library. Until end of turn, you may cast one of those cards without paying it's mana cost.
{w}{w}{u}{u}{b}{b}{r}{r}{g}{g},{t}: You may cast any number of cards exiled by Door to Infinity without paying their mana cost.