For the love of all that is good in this sad dying world.
Just lost a very very long post and feeling very pissed. Why on earth does CFC do the "you were logged in in a previous session so BEEP post destroyed"? I know that it doesn't work that way on RB, at least.
Anyway, summary. This is incredibly bare bones because of mood so ask me to expand if you don't understand or get a point:
Mithril marauders: You may have a point. I left as is so spawns wouldn't be so sucky. I don't think anyone would ever build over zombies. So apples and oranges comparing, as Sheiam have different model to other civs. Maybe zombies are OP'd with Mithril actually.
Mobius Witchs: Compare to vamps. Vamps are better (IMO) because reasons (faster to setup, have most useful spheres, feasting, blah blah blah. Therefore if priced, should be cheaper then Vampires. Lack of free spell spheres + xp generation being quicker means that all-mage armies go the classical route not Witchs (IMO) so witchs are mainly good for Averax/Os-Gabella. Even then can't count on free spheres and needing mobility plus 2 levels for promotions means you basically need L3 anyway...so just get a adept? Of course, you can compensate by ignoring mobility or converting nodes and so on, but it still takes a bit of setup and probably requires xp civics, so adept-mage normal route is better for msot mage armies.
There was more but god its late. Summary they may be overpowered, but sheaim need the boost, it probably isn't by much anyway, and it doesn't seem to supersede the normal process of adepts for a ARC army, so only issues will be getting a too-early mage and making it easier for non-ARC leaders to supplement their army. Given expense of buildings/Witch itself and earlier mentioned issues, I don't think the first will be overwhelming, and the second is sort of what Gate creatures are for.
Tbh I thought it would be more overpowered, and then testing showed the xp issues.
Agree to disagree on Luchuirp

Unless you want to duel?
(Genuine open offer, btw)