I would like to ask the more observant reader to Ignore the fact that this new content is being referred to as Free-LC, because this isn't really the time or the place to bring up Creative Assembly's long and unpleasant history with paid content but I will say that this is a much needed and very appreciated change from the way we've seen them operate in previous years.
This update brings 11 new maps free and two new Legendary Lords: the Grey Wizard and the Jade Wizard. These maps will be available for multiplayer and custom battles as well as scattered around the world map for use in your Total War: Warhammer campaign. Some of these battle maps are now linked to special campaign missions and as such wont be seen unless you're in a custom battle or you're going through a game as a specific faction, say the Wood Elves, for example.
I highly advise that you go and watch the video because these maps do actually look quite good and will make a fine addition to the game. You will learn a little bit about the Grey Wizard and the Jade Wizard and their specific play styles. Now if you want these guys you do have to go to the Steam page and download them yourself. But you wont be able to download them until December 8th. You can find them here and here respectively.