Got my first Mastery Level 7 token on...
...Vayne.
People see her as "broken" or toxic to play against. It's true once she gets a lead, it's hard to stop her, but she's also relatively easy to shut down.
The fact the S took so many games to gain from my last S(only got S- grades for a while) made me feel so satisfied. Having S grades require so much effort makes the ML7 token really worth it and respectable. It truly does showcase at least some tier of mastery.
Last time I asked how to get a S, people said CS was not a factor and was insulted for thinking so[regular boards day]. This is completely false as I had the same KDR from a different game, less objectives, but the 100 more CS. KDR was about 8.0. Other users have also informed me that CS is a key factor to getting a S.
To be honest, I was hoping getting a S would net me a chest though. Hextech chests don't seem to come anymore even though I have keys.