I just thought of a trick, not sure if it works or not, haven't tried it and I'm at stupid old work.
If you use a Sov's daughter to imbue your champions as casters and then marry the girl off, do the champions remain imbued and do they still cost mana upkeep? Someone try it, if not, I won't be able to for awhile, I have to have an important talk with the girlfriend after work, so that means she is either breaking up with me or wants to move in...and either way, I'll be too busy crying to play the game.