Of course, an expansion for the game doesn’t just mean new cards, and there are also new card backs on deck for reaching appropriate ranks in competitive play in December, January, and February, as well as a new board layout to really capture the cruelty of Gadgetzan’s walkways. The patch also makes some minor updates to AI, the crafting interface, and squashes a few bugs along the way. If you haven’t already patched up the game, do so before tomorrow, so you’re ready to take on the nasty avenues of the only decently sized city in Tanaris in Hearthstone. And only Hearthstone, it’ll probably get updated in Azeroth around the same time that cross-faction chat is implemented.
Source: Official Site