The new Battletome gives additional rules and updates to the Daughters Of Khaine on the battlefield. As you might imagine, it makes them even more murderous than they were already. As one of the most well-loved armies in the range, it's good that they are getting a leg up.
They don't get any new miniatures apart from this new set of Endless Spells which can be introduced into your games. Who wouldn't want a hurricane of blades and blood?