I used the old version of the Sharkey model. That's the fallen version of Saruman at the scourging of the shire. This guy was fun to paint up and as far as rules go I guess I'd just use him as a another wizard and maybe just swap out one spell for a "blue" spell what ever that may be.
This does leave me with a predicament though. I only have 1 of the 5 wizards left. Palando the Blue. I can't think of any other models for him... Is there an alternate version of one of the wizards I can use? Is there an alternate company with similar sculpts? I guess I'll have to figure something out.