rank

S- 93% better then other players S 95% better S+ is 97% better

The algorithm for your post game Grade/rank awarded, looks at a couple of things, Kills/Death, kill participation, damage output compared to your team, overall dmg done to structures as well as warding....I have seen players with 14-4 score that did not get S cause they only KS or picked kills of without too much work, I have had an Orn game, where I ended up 6-8-7 but got S- cause I had the second highest dmg in team, 80% kill participation and good farm.

You have to excel at whatever role you play the champion in.

Lee sin jungle, you'll have to do better than MOST of the other players using Lee Sin in jungle... However, if you take LEE SIN support, you only have to beat the players using Lee Sin as Support, which is far less.

Another few rules I've come to learn none of these are actual rules, but they feel like they work more often then not.

If you're a jungler, end the game with at least 100 farm usually I get ahead early game, then use the last few minutes of the game to farm empty lanes Have a good KDA. Buy/use a ton of wards (buy the pink wards, and use your trinket wards as often as possible) If you can heal/shield, do that as much as possible, even in times where it seems pointless (shielding jungler from camps or adcs from minion waves)

Using these I've been able to get mastery 7 on J4 Lee Sin Kha Zix Blitzcrank Lux Amumu Diana Ekko, and Kayn.

Good Luck.