Nagash Stacks in the Backfield (as Archaon)

So.... Nagash just popped and I have three stacks of elite Undead parked next to my Capital in the Chaos Wastes. No attrition, very, very powerful units, and the best I could muster doesn't appear to be enough. They'll hollow out my economy before I can meaningfully respond. WoC recruitment is slow, and Armies are too expensive to park a good one and it takes too long to bring them back from the Front. So I'm starting over, trying something else, but it feels like such a defeat. Thoughts? Tips?