Right now I am thinking of using any of the following effects:
Drain Speed (I have found from using Hatred's Soul, that even just a little of this can freeze some enemies to the spot, and make it very hard for the rest to ever reach you).
Paralyze (always handy in a pinch.
Silence (her chosen enemy is Necromancers, so an obvious choice. But I cannot help but think that Paralyze is better, as it is useful against all types, while Silence is really only good against magicians)
Weakness to Magikca (being that she is a spellcaster, this would be an excellent set-up attack. Perhaps when combined with Drain Speed this might be the front-runner).