I'm trying to rp a Thalmor character and was wondering. What type of magic do they use? and What magic do they consider taboo?
Also do they worship any Gods or none? I know most Altmer worship the Aedra, but I don't know enough of the Dominion.
Any type of magic is open game, though the Altmer have a special connection to mysticism and, as far as racial bonuses are concerned (the biggest bonuses received by Altmer in Skyrim, Oblivion, and Morrowind: illusion, alteration, destruction, enchanting, and alchemy.
Lore-wise, they refer to something called forgotten "Dawn Magicks" in Skyrim. Not sure what that consists of.
The Thalmor (and High Elves in general) have no magical taboos that I can think of. Communing with daedra, as it is seen pretty much anywhere, is generally frowned upon; but not nearly as much as it is in human cultures, let alone in provinces like Hammerfell or Skyrim.
I suspect the Thalmor generally adhere to the traditional Altmeri pantheon. Like those Gelebor refers to in Dawnguard - Auriel, Trinimac, Syrabane, Jeffre (Y'ffre), Phynaster, Xarxes, etc.
Edit: Auriel has a special significance. If you look at the Thalmor banners, they display a very stylized golden eagle - Auriel's traditional iconography.