Today's Hearthstone: Curse of Naxxramas card preview is the creepy-crawly Anub'ar Ambusher. This rogue-only card has the text "Deathrattle: Return a friendly minion to your hand." That could be handy for recalling creatures with battlecries or frustrating if you have a bunch of buffed up beasties out. As with all Hearthstone cards, using the Anub'ar Ambusher to best effect will require some strategy.
As interesting as these tiny previews are, they still don't hint at a release date for Naxxramas beyond this summer. Hopefully we'll be seeing more than previews soon!