Playing through Durlag's now, I'm pretty high level - have access to 5 lvl spell. So when I go in and break the mirror, my clone starts the fight with a Spell Trigger, which contains Death spell among others. He's also gets Protection from Magical Weapons and even Spell Trap. That's just over the top.
I've general AI and Improved Durlag's installed, but not Smarter mages.