[Belcarl]

Why dont you use communion? Only requires S1 and Thaumaturgy lvl 1.

2 slaves gives +1 to all paths, 4 +2, 8 +3 and so forth.
Celestial masters have a broader range of paths then the theurgs, so you have an easier acess to most of the low path required battlefield spells.

if you are afraid of magic duel, dont forget that your communion slaves gets the same buffs that your communion master gets, asuming they are in communion when its cast. So if you set a second communion master to cast Light of the northern star (or carry the banner with the same effect) you suddenly have a lot of S2 slaves that the enemy magic duelant risk of losing against, and you really dont care much about. Since the Magic duel target is random among your astral mages. Your slave mage is expendable, his is most likely not.