Seems we have a preview here for Naxxramas over at the official WoW: TCG site. Specifically, we have two cards on the agenda.
One is called Calamity’s Grasp which is for both Rogues and Shamans. The idea behind it seems to be that you play the card and select a card type that you want to destroy on your opponent’s side. You sacrifice an identical type so you can remove your opponent’s card. It’s a risky move, mind you, but if you have filler cards or quests to get those types of cards back then I can see how the ends justify the means.
The next card is Wall of Terror which grants Warriors and Paladins a nice +3 armour bonus. The big thing, it seems, is that it eliminates your opponent’s cards back to their hand, having them to resource everything back out again. This can be particularly handy, I would assume, if the opponent had lots of higher cost items, allies and equipment. Still pretty darn cool though.
For more info check out the Preview.