For when we eventually expand to rank 10 mastery, there should be some kind of cosmetic

I get it if it is not a skin (too much lost revenue) or a special chroma (too much work to make a chroma for every single champion in the game).

So, how about a hat?

A little golden crown that you can toggle on and off, that just sits on your champions model.

Kinda like the Draven day thing, except not horrible.