While not Masters per se (cause who doesn't like a coat of fresh paint), they really really really do need a competent ALL-INCLUSIVE mage cabal (none of this crap where even a conjurer can't find a home - I'm looking directly at you entropy... a once likely chance to have a reason to die masochistically as a chaos conji).

But the Cabal should reflect what Outlander has done with ethos and alignment on what/which skills members get. Like masters, each mage sect should have something unique:
Conjuration
Invocation
Necromancy
Alteration/Transmutation (someone clever aptly divide up the schools in which shapeshifter and transmuter are separate)

Possible Class Exceptions off top of my head: Thief -arcane path requirement, Ranger -animist path requirement

Then alignment flavors for Good, Neutral, Evil respectively
Then ethos flavors for Orderly, Neutral, Chaotic

Then a final flavor to really one-up the Outlander mix: Good/Orderly, Good/Neutral, Good/Chaotic, Neutral/Orderly, Neutral/Neutral, Neutral/Chaotic, Evil/Orderly, Evil/Neutral, Evil/Chaotic
Then in closing, a semblance of rank progression... gaining entrance shouldn't be overly difficult, true acceptance of all mages wishing to contribute to the cause, but then progression in the mage sect. An arch-mage leader position that could gain a perk from each of the schools of magic, Individual Sect Masters that gain the individual top perk of their school of magic.

On the side, Could you imagine the amount of return players that would come back for either this cabal or to revitalize Battle with some honest-to-good enemies?