What about letting mages organize similar to the thieves guild? It would allow mages to form community without all the politics of a regular cabal, and an alternative to Scion/Nexus . Its aim would be to explore magical knowledge and preserve it, regardless of ethos. No powers or anything, just a way to communicate with the guild community at large. Maybe (in future) have a magical library similar to the Lyceum.

Perhaps the guild could be at odds with (though not directly opposed to) Scion, .. while the guild would still consider necromancy and other dark magics as viable paths of magic, they feel the Scions take it to a destructive end.. I suppose you could say the guild would be ruled by spheres Magic and Knowledge?

In regard to Nexus, they would seem too involved in politics to promote careful study of the arcane, though there would be some sort of strong relationship between nexuns and the guild, as the isle guards one of the rifts.. and wouldn't kill them on sight.

Their main enemies would be Battle, and perhaps sometimes Scion.. they could have an interesting love/hate relationship with Scion.. the guild trying to keep them under control. (I have no experience with Empire, maybe they would oppose an organization of mages as well?)

Would be open to all alignments and races, though chaotic may seem less prone to joining.. I would motion to include only pure mage classes, so no A-Ps, animists, or mystic thieves.. I'm not sure about necromancers.. I think they should have a place, but not sure how the guild would handle them.. they could be like the guilds dirty little secret, trying to keep the necros from causing too much of an issue with the citizens. Or if that doesn't work, theres always Scion for them.

What do you think? I know it needs more fleshing.. i admit i dont know a great deal about the history of Thera, and I may be off on some of the cabal interrelationships to make a new guild fit in perfectly, but I think this could work.