I just had a cool idea for a high end objective: classic crusaders only. Looking at my formation, only 5 out of my 13 are classic, and soon to be 4. (And it would be 2 if I had been playing for longer.) So why not make an objective that forces us to use only the original 20? It'd have to be a relatively late game objective so the people doing it have the majority of event crusaders, but I think it'd be an interesting challenge.