Please take care with the balancing when you guys do so. I am currently playing with a 5.0 quantity zombie options setting and when a necro is around with 30+ dead zombies that you can’t pulp or butcher yet because you are still fighting the other 20 or so, they can become pretty fucking scary. I have had 2 occasions where they res a handful around you in a single turn while you are trying to control a specific choke point… yeah, nothing lame about that.
You might need to get a little more complex with this one. What worked really nicely on the necro’s part is when they were in the back of a pack meaning that you couldn’t rush them you had to try and take care of at least some of the others first. The point is, you are left with a tough decision. The longer you leave them to try whittle down the pack, the more opportunity you leave the necro to raise the bitches again, but rushing him too early means you might get your ass handed to you while moving through the pack.
Imo, a combination of what you intend to do, with AI for the necro to not run away, but try and dynamically position himself at the back of the pack considering your position every turn would lend more survival time to him and offer him the opportunity to res some of the fallen, while making your decision on how to handle the situation interesting.