I like this 4 horseman approach they are going with. Seems pretty awesome but a little backwards because death shouldn't come first. At least i think that is what they are going for. Nagash and undead represent death, Nurgle is obviously pestilence, i'm assuming the Skaven rumors may be their version of famine since everything is being destroyed down to the dirt of the lands by them. or maybe it will be ogres because they are all about consuming everything in their wake, and i would say war would be represented by Khorne but that is too obvious and i would think that that orcs and goblins might fit that role because of Grimgor and Skarsnik being the living embodiments of Gork and Mork respectively, two war gods.