Upper Deck Entertainment has a UDE Points Store where you can purchase the Ogre Disguise Trinket. Unlike the Murloc Suit obtained at BlizzCon which is a buff that disappears after entering combat, the Ogre Disguise Trinket (as you can tell by its name) takes up a trinket slot but remains on during battle.
All 25 members of Nihilum's raid donned their Ogre Disguise Trinkets and killed Archimonde appearing in nothing but loincloths and armbands. It is unclear if they purchased these trinkets themselves (they are fans of the TCG and one of them has the Spectral Tiger Mount) or if UDE provided them.
For the full story and more screenshots, go to the article at the UDE website. Or go take a look at how to get UDE points and what other items you can get with them.
(Update: <fires unpaid proofreader> Errors fixed. Sorry for the mixup.)