Summon monstrous beasts, wurms, and hydras, and use them to stomp your opponent's forces like insects. Then cast Overwhelming Stampede to give your forces a lethal boost of power.
The "Stampede of Beasts" deck uses fearsome creatures to trample the opposition. Start the game off with Llanowar Elves and Sylvan Ranger. They'll help you get the mana you need to cast the large creatures that form the bulk of your offense. Garruk's Packleader, Spined Wurm, Yavimaya Wurm, and Duskdale Wurm all demand answers from your opponent. But none of these creatures is the largest creature in your deck: Protean Hydra's size is limited only by the mana you have when you cast it.

Your opponent will play creatures as well, but that's where your spells come in. Use your red spells only to get your opponent's creatures out of the way of your own. Making your own creatures bigger with Giant Growth or unblockable with Whispersilk Cloak will get them past your opponent's defense. Your best spell is Overwhelming Stampede. It gives each of your creatures +X/+X, where X is the greatest power among creatures you control, as well as trample, which lets your blocked creatures deal their extra damage to your opponent.

You can improve your "Stampede of Beasts" deck with other Magic 2011 cards. Cudgel Troll is a 4/3 creature for four mana, and thanks to its regeneration ability, it can't be destroyed if you have a green mana to spare. Mitotic Slime is a 4/4 creature that when it goes to the graveyard, you get two 2/2 Ooze tokens. And when each of those die, you get two 1/1 Ooze tokens! Finally, Primeval Titan is a 6/6 creature with trample for six mana that puts two lands from your library onto the battlefield when it enters the battlefield or attacks. If it doesn't finish the game, the Fireball or Protean Hydra that follows it up certainly will.