I'm a fan of existential cosmic threats personally. Not the world shattering kind, but ones that slowly spread darkness until everybody has no choice but to submit to see anymore. Invasion of ineffible outsider entities that seek to corrupt the world to more their liking.
Also, to continue the allegory, after Realm War 1, the Red Wizards had a cleaning of house where they disposed of all the ancient lich wizards and formed a new order for the living. Just make the claim that necromancy is the work of the gods and no longer allowed. They're still evil despotic Thayan wizards, but they can at least say "we're not that."
(I had an idea for some games that I never quite got finished. Lovecraft in WW2 with magic/psychic powers based on Wilhelm Reich's Orgone theory and mad science tech based on Tesla's death rays. First game was to be called Flying Saucers of the SS. I actually did get the background written up as part of NaNoWriMo a decade or two ago. The idea was the PCs were Nazi Lovecraftian cult hunters. I was almost finished with the fiction when I learned of The Laundry series and held off reading it until I was finsihed. The second idea had more promise I though, Flying Saucers of the KGB. Cold War era game set in 1968, both superpowers are both exploring the new psychic and other tech but it was a world where youth cults were possibly the more dangerous threat. PCs were cult investigators and the theme was that they didn't know who to trust. The KGB agents were at least human and doing the same work, but they could be corrupted, but then again, so could their own people.