You could have played Magic from the moment you got to Gen Con until the last minutes as they were breaking down the greatest four days in gaming. There were Block Championships, Vintage Championships, Legacy Championships, Grand Melee booster drafts, 8-man booster drafts -- and of course, the U.S. National Championship. There were a handful of cards that stood out from the rest of the hundreds and hundreds of different cards that saw play.
Slash Panther
This is a card that is a decent in draft and has seen virtually zero play in Block, Standard, Legacy, and Extended tournaments and yet it is fast becoming a Vintage staple. You can power it out on turn one with a Mishra's Workshop and a Mox. Add in a Phyrexian Metamorph and you have a turn three kill against an unwary opponent. It is also shockingly good at killing Jace, the Mind Sculptor out of nowhere. In the Vintage Championships Ryan Glacklin took the deck as far as fourth place.
Scavenging Ooze
Reed Hartman took a single copy of this Commander card -- a never-legal-in-Standard addition to the four Tarmogoyfs he already played. According to the Legacy Championships finalist the card may have actually been better than the first four Tarmogoyfs when all was said and done.
Goblin Fireslinger
What would you take out of your Magic 2012 booster pack if you were drafting for the National championship; Flameblast Dragon or Goblin Fireslinger? According to Christian Valenti -- who like you at home thought "dragon" -- he should have taken the Fireslinger. The card broke out this weekend as one of the staples of the aggressive goblin draft archetype that carried multiple people through their draft pods without a loss. Valenti managed to pull that pod out despite being "stuck" with a dragon.
Azure Mage
Everyone likes card drawing -- you need only look at the Consecrated Sphinx on either side of the finals -- but it was the ChannelFirebal crew that put three players into the Top 8 of Nationals with the CawBlade mirror breaking Azure Mage in their sideboard. The perfect card to straddle control and beat down , you can expect to see CawBlade players everywhere following suit in in the coming weeks.
Karn Liberated
US National Champion Ali Aintrazi showed everyone who the new Planeswalker on the block is when he used the "vindicate" ability on Karn to take care of pesky lands, chump blocking Squadron Hawks, and a Consecrated Sphinx. He could have even started a new game in the last game but decided that he would rather just win instead with his army of Planeswalkers that included Karn, Liliana Vess, and Jace Beleren.