@Meddler/Scruffy/etc. - How do you go about balancing a Champion Concept?

One of the hardest things when making a concept is making sure its balanced; not just in skill design, but numerically too. You look at how numbers are buffed/nerfed each patch and you realize how even getting slightly off the mark leads to a Champion being broken. Or if you get numbers too low, no one will think it's any good and will start comparing it to other Champions who are "stronger".

I've been at the Concept Creation game for years now, but I still continually make mistakes when it comes to Champion balance. I'm sure you guys do too, but I do it on a regular basis.

Got any advice on how to balance out something like this? (yes, shameless advertising) #http://boards.na.leagueoflegends.com/en/c/skin-champion-concepts/YJA491Te-celes-the-dark-crusader