Creature — Beast 7/7, 5GG (7)

Trample
Play with the top card of your library revealed.
You may cast the top card of your library if it's a creature card. (Do this only any time you could cast that creature card. You still pay the spell's costs.)
Illus. Kev Walker

9/22/2011: Normally, Garruk's Horde allows you to cast the top card of your library if it's a creature card, it's your main phase, and the stack is empty. If that creature card has flash, you'll be able to cast it at the time you could cast an instant, even on an opponent's turn.
9/22/2011: You'll still pay all costs for that spell, including additional costs. You may also pay alternative costs.
9/22/2011: While playing with the top card of your library revealed, if you draw multiple cards, reveal each one before you draw it.
9/22/2011: The top card of your library is not in your hand. You can't discard it.
9/22/2011: If the top card of your library is Dryad Arbor (the only card that's both a creature and a land), you can't play it this way. Dryad Arbor can't be cast as a spell.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Extended (Type 1.X)
Legal in Classic (MTGO)
Legal in Commander
Legal in Modern