I'm a simple warrior, but I like using Resurrection, Teleport, Dragon Arrows, and spells against undead that are related to light, healing allies, and killing undead. Blessing is also useful; it's a good time to recharge some "double shot" spells, as well as spells that maximize damage, and speed boosts can also be applied from time to time. For variety, you can also unleash a phoenix on someone. In general, I'm not using Chaos magic much right now, but the other schools are very welcome.