How about a death spiral? It's easy with a massive integer loop spawning from 1 to 36, then simply reverse it to make a complete circle, if done correctly with the right SFX, will look awesome. Exists in the database somewhere.
Last thing I can think of, is like a giant shadow dummy dragon with thin transparency and no tint that arises from the death knight's body, and then whatever bonuses you want. It's kind of likt Bladewing's Thrall