I, personally like mages in general. And in this game, I suppose my favourite faction would be
the Elves. The problem I see is that RTS games lack the RPG element whereby one can associate themselves with one single player (i.e. an Elven Mage.) All players are, essentially, disposable units, or cannon fodder, put bluntly. Hero units
would work, however. So if there was a hero mage, or a clan/guild of 'hero' mages within the storyline, or implemented in the game, then this would shape out in accordance to the OP's wishes. I would still consider the proposal, however. Just wish to see how imaginative others are here.
Any comments by RWS on the above?