Oh yeah, I thought of another one:

-1st person mode challenge. Personally, I think this is the most insane of them all, since if you do this, you will not be able to use R1 or Square, as they will take you out of 1st person mode. That means no Guard or Lock-on! Though, you can still use reaction commands, since it is necessary in boss battles. I also don't believe this is even possible; but if you want, go ahead and try.