This, while not making it super OP but still advantageous to use given the negative effects of being 'caught' using it. There could be quest lines dealing with a split in the conjuration college or a mix of several colleges middle-upper members who break apart and form their own sinister sect in the wilds.

Of course being associated with the will make most people ill and not want to speak with the character.

Rather than a whole new element, it would make more sense to have necromancy as a faction, wouldn't it? Due to Skyrim being at war with itselfn necromancy is on the rise because of all the political issues, and nothing there to stop them. Or something. >_>

...a subdivision of Conjuration

Personally, I don't think a Necromancy faction makes any more sense than a Conjuration or Illusion faction. Morrowind is the only place that had Necromancy as illegal, and the Mages Guild is supposed to be dead, so Necromancy could be studied right alongside any other school of magic.

I think magic under the "flesh" element would pretty much be classified as Necromancy. Relmyna didn't discover it, she just excelled in it. Flesh Atronachs have been around since Daggerfall.

I hope it's more than just a spell though, there can be such a deep necromantic activity in Skyrim if they take time to think about it, because my head is exploding with ideas (some of which can be found in other threads).

Yeah. As far as I know, Traven was the first Arch mage to ban Necromancy. But, he's long dead, and from what I’ve heard, the Guild has been disbanded.
Also, when I think about it, Relmena was seemingly bringing her victims back to life after she'd killed them. My first though was that they were just zombies, but they seemed to react to that pain spell she cast. And in her notes, it said she kept on brining back some wood elf girl to fight her flesh hounds. Doesn't mean that she had achieved the goal of Necromancy? And wouldn’t that make her like, the best Necromancer ever?