I use counters and a timer to determine when a spell is ready to be cast and Debug.SendAnimationEvent to get the actor to do some kind of appropriate animation for the cast. It's not perfect, but the effect can be impressive.
I wish I COULD get a magic-user's combatstyle to work for, say, the Giant model, but it just doesn't seem to happen

I suspect the models I'm using just lack Cast animations and that's all there is to it.