Not Sure if this deck is going to be any good, but I thought it would be cool. Saruman and doomed cards do work well with the low starting threat that The Grey Wanderer ives, although I still think your threat is going to get high pretty quickly. Strider goes on him right away, obviously, so he can quest for 4 without exhausting. If you use The Grey Wanderer to ready him, he can defend (hopefully with Protector of Lórien) and attack for 4 . Saruman's Staff is the card to mulligan for, because it will either get doomed events or stop you from raising your threat too much. Keys of Orthanc is another clutch card to give him resources. Also, look for Resourceful early when you're still in secrecy.
Ents are the allies here, and I do realize the irony. However, perhaps this is the Saruman that did love all things growing, before he was corrupted by the ring and taken by the will of Sauron. Regardless, Defiant Challenge is a clutch card with Ents to get them going even quicker.
The last little trick in here is Helm of Secrecy, which can be summoned with Word of Command when you need it. With it, you can swap Saruman for Lore Aragorn and reduce your threat to 13, giving you a lot more rounds to win. This can be done whenever, but is generally a last effort if you are about to be eliminated by threat.
Thoughts/comments are appreciated!
I forgot about Power of Orthanc (for quests with condition attachments only)