The Fox, Heir-to-the-Heir

Vigilance

At the beginning of your upkeep, exile the top card
of your library face down. (You can't look at it.)

{2}{g},{t}: Reveal all cards exiled with The Fox,
Heir-to-the-Heir. Until end of turn, you may play
lands and cast spells from the cards revealed this
way and you may cast those spells without paying
their mana cost.