I would say Frost Destruction as well, but you don't want too much magic you said, and plus everything in Skyrim resists Frost. Maybe you could even make him/her a Vampire too? Unless you've already done Vampires and are bored of them as well.
I had a build very similar to that, I went with light armor though, and I got Volendrung the Malacath artifact for my hammer. I found with Illusion, I had to stay sneaky at least a bit, so as soon as I used Fury on someone they didn't just detect me and attack me, but attack their friends instead. Then as I wait for one of them to die, I am still hidden as my Magicka recharges, then I can raise one of the fallen enemies and pull out my hammer to battle.