Hey, Caits!  I was thinking that one way Nero could be used is to initiate a minor arc like you sometimes see in filler episodes, in which everyone is transformed into something.  He has the ability to use his curses, particularly an unfocused Law of Atavism, on a large scale.  I'm not saying that he's going to randomly do it, but if you feel like goofing around a little in that regard, I can provide.