There will always be cheaters who would try to find a way to get their benefit. Some Rory himself can't even help, as Robin said all he needs to do is not make it a huge advantage to see through trees and such. As for the HP why not some "cheap programming". Basically meaning how about if the max hp for everyone is 50 and every damage are 21 or 15 or 10 or idk how damage for jutsu will be done, instead make it a percent of health? I'm not sure how that would work through since I have no knowledge of any other programming then DM.