League of Legends has added a new way for players to progress. The Champion Mastery system gives players rewards for gaining experience with Champions.
At the end of each match, the game will award you points based on how well you and your team performed. Once you earn enough points, your champion will hit a new Mastery level. Each of the five levels comes with different cosmetic rewards.
For example, your character will get a new title every time they level up. The title depends on their main role:
The Champion Mastery system may have additional rewards in the future. Riot says that they probably won't give away skins but they're considering other "unique" gifts. I'm personally hoping that they tie chromas to the Champion Mastery system.
Riot says in the FAQ for Champion Mastery that they want to avoid Champion Mastery from feeling like a grind. It should take about 15 to 30 games to get one Champion to level 5. Again, your point rewards vary based on your performance so it'll take longer if you're playing badly.
"We take a series of performance metrics and compare how you do to all other players in your region in your champion / position combination," Riot explained. "It is percentile driven - so earning a high score means you performed in the top x% of players on that champ in that position. The grade itself governs the point gains."
Even if you're terrible, though, you can eventually soldier through. You won't lose Champion Mastery points by losing and/or sucking. Furthermore, points won't decay if you haven't played a character in a while.
That said, Riot doesn't want to make this a complete cakewalk. You can't just max out Champion Mastery by playing bot games. You'll need to queue up for normal, team builder, or ranked PvP matches. Furthermore, you won't earn points by playing Dominion or ARAM modes. The same probably goes for any featured game modes Riot may introduce in the near future.
I fully expect to see a few players AFKing their way through Normal matches to grind up their Mastery level as easily as possible. Riot says that your score will be penalized for this behavior but as long as they're getting something for sitting through a match while playing Hearthstone on their phone, someone's going to try.