Alright I'm being an ideas leech here but...
combine this (cirith)
I happen to be working on something: a guild of publicly powerful people (guildmasters, nobility, generals and some more shady guilds) who use their influence in their guilds and other cooperations to remove cetrain lore from public knowledge: scrolls are conficated, Tamrielic lore gets rewritten, and the artifacts and other secrets are either locked in a vault or left untouched and with nobody outside the guild knowing of it's existance.
with this (con-tur-eh)
Or if you want to stick with guilds and fit in zombies/undead you could do a necromancer guild.
And you get a plausible, motivated group - Necromancy is a controvertial issue in Tamriel having only recently been banned by the Mages Guild and not necessarily entirely illegal. This shadow group represents people of reasonable power and repute among the elite of Cyrodil who wish to make necromancy accepted once more, largely made up of magically inclined people who have a vested interest in the art of necromancy -> side 1
On the far side you have other radicals pressing for the complete barring of the use of soul gems (they are extremely cruel artifacts that obliterate the soul of the creature imprisoned within -> think a daedra rights group) these people are unlikely to be involved in magic because of their views on gems maybe over here we have the devout, both clergy of the Nine and Daedra worshippers -> side 2
Then obviously in the middle you have the majority of people and most mages -> side 3
from here you do a roleplay about the political intrigue and terror actions of the two radical groups and how your characters get entangled in the warring.
how does that sound