I think you could even make an indestructible using hybrid sets instead of heavy armor and using all the little offensive spells (blast, rend, needle etc.).
Not as efficient as a pure mage, more like "surprise, I'm not a noob and I don't care too much about your fireball".

[Linked Image from w3.the-kgb.com][Linked Image from w3.the-kgb.com]