[vfb]

Fatigue does reset when you reincarnate as a soulless, and you do keep items (if you don't lose an arm). But I think it's more likely you'll rout Vanheim before your mages die. (Depending on how many mages you're planning on sending, it's always possible he'll just charge up and kill you). You don't even know if he'll just sneak the Vans out. And once you take the province, what stops Van from trapezing in a bunch of A3s/A4s to blast you to death with thunderstrikes?

Even if you do manage to pull this off, you'll end up with a bunch of afflicted mages with horrible MR and half the HP of a Starspawn. You've already got cheap chaff that can't be banished: your Lobo Guards. If you really want some Soulless of Atlantis or something, cast Carrion Reanimation, it's only 5D.

If you're determined to make some mages undead (and you've got the Chalice or GoH), you're probably best off attacking a neighboring province conventionally, using Soul Vortex + Paralyze (to make the battle last long enough), and convert some Starspawn mages to undead too, to save on their upkeep. And bring along a ton of Lobo Guards to convert to undead too.