Champion Mastery is currently divided into 7 levels, with level 7 being the highest. To progress through the levels, a player need to play games on your champion and earn champion points (CP).

Is there mastery level 8?

There are 7 levels of Champion Mastery currently obtainable, distinguished by crests.

What is the highest mastery you can get?

Earning CP will allow you to gain Mastery Levels (up to level 5) in that champion and earn rewards as you progress. Points are based on your performance, your team's performance, the length of the game, win vs. loss, and a few other factors.