So i know this helped me a ton, after failing Denny so many times, i realized you can climb the walls.  So simply stay up above him on the walls, and he'll grab his slave, and you can go down and hurt him.  Repeat until he's dead.

Just figured this out wow >_>. Well good thing you beat it.

Its a good approach to used on most big units when walls are present, run up the wall jump behind them and give a chain saw to the spine.