[Lazy_Perfectionist]

Reinvig of 7 and death four? 0 aggregate fatigue?
Raise Skeletons has fatigue 40.
Animate Skeleton has fatigue 30. I can see how negation takes place with this spell...

but raise skeletons has fatigue of 40, path 2. At D4, the cost would be 40 / (excess levels+1) or 13.

If they didn't have that high MR, you could drain life to recover fatigue- but as they do... No.

If you have the time and the mages, Darkness can help. Even if your army consists of regular troops, it affects elites more, working to your advantage. Plus it will significantly help with the survival of your skelies/ghosts.

For the record, you can spam ethereal troops. Niefel Giants do not have a magical weapon and the area-affect weapons they do get at con 4 are cold and death damage. So dispossessed spirits may get hit by a magical weapon, but only one at a time.

Now how effective any of this is? I'll probably be finding out, starting next to Niefelheim in Doom Chicken. None of the above is a tested strategy yet.