You might try searching for Ermor instead. I'm pretty sure there have been discussions on how to deal with Ermor, regardless of what nation you're playing. As a matter of fact, I distinctly recall a thread only a few days ago. To quote one post from that thread; "Priets, priests, and more priests."
Though I believe the thread was asking how to deal with Ermor's living units rather than the undead.
I currently have a game going where I'm playing Marignon, and Ermor is one of the active AI's. Have yet to engage in battle with them though. I sent a scout and an assassin over their way, since I want to keep tabs on them. They keep casting global enchantments that I have to keep dispelling, which annoys me, so I have one mage who regularly casts 'seeking arrow' in their home province, and any province I see with a large army. I've also employed the assassin with good effect. I
have recruited a half-dozen priests in anticipation of the coming conflict, as we now own bordering provinces.
This is my first game as Marignon though, so that's all I can offer.