http://www.wizards.com/Magic/Magazine/Article.aspx?x=mtg/daily/arcana/1152

In the Gruul Clans, bigger is better, and with the "Gruul Goliaths" deck, you'll be king of the hill. Gruul creatures crave battle so much, sometimes they don't even wait until they're on the battlefield! The new bloodrush mechanic allows you to discard a creature to pump up an attacking creature. With these creatures essentially joining the fray, you should be able to trump any blockers your opponent can produce. When in doubt, attack!

Cards like Rubblehulk and Zhur-Taa Swine are both big for their cost and have aggressive bloodrush costs to boot. Attack with your small creatures early. If they're blocked, bloodrush can help you smash whatever's in their way. If your opponents aren't blocking much, those creatures can hit the battlefield and keep up the attack. It's a win-win situation.

The huge creatures in this deck put massive pressure on your opponent, especially if you cast them ahead of schedule. Ranger's Path ramps you all the way from four to six mana, meaning you can untap on turn five and cast the mighty 7/6 Ruination Wurm! Arbor Elf and Gruul Keyrune also provide some leaps in mana production.

Large, ruthless creatures are always welcome in a Gruul deck, and Magic offers plenty to choose from. Elderscale Wurm from the Magic 2013 core set is a perfect addition. It's a sturdy 7/7 trampling behemoth that can keep your life total at 7 or more. The soulbond mechanic from the Avacyn Restored set is also definitely worth checking out. Soulbond allows two creatures to pair together, providing a mutual boost to both of them. If large creaturesare good, large creatures working together is even better!