As an alternative, the manual states (and my experience at least has confirmed) that any Undead Priest can Reanimate Undead. That being the case, you can summon up a Shade or a Mound King simply to prophetize them to reanimate undead.
This would get the 'factory' started much earlier than waiting for a Mound Fiend.
Not that its valid for Niefelheim, but that same trick also works on demons. I had some experiments with Yomi a while back.
As well, LA Atlantis has W3D?1 priest-mages available at the capital. Cast twiceborn, get them killed off - in your dominion- and then you've got upkeep-free reanimation machines.. Lose the special abilities like sailing, thoguh.
I don't think reanimating is a big enough deal to warrant anything special to get it. For Niefel it might be though. I know with the cbm version of the Reanimation spell (which doesn't cost 10 gems, it's 2 or something) that it's actually worth using for them.