Speak with Caza'rez in the Blood Furnace.
Caza'rez awaits you within the Blood Furnace. He's already cleared out a small area and has our scryers hard at work figuring out what's going on down there.
But I don't trust that scrying will be enough. I'm sure Caza'rez has plans in mind for a solid blade or two. I want you to go there and lend him your expertise in dealing with the fel orcs.