While removing toxicity from the game is one of Riot’s main ambitions, promoting positive behavior is essential in the community too. Riot has made different approaches to support positive behavior in the League of Legends community.
Positive reinforcements show their biggest effect on neutral players. It motivates them to go a little further to becoming a positive influence in their games. While these rewards are usually appreciated, they can also have a negative effect on already positive players. This is called “Overjustification Effect”  
Following Rewards in the game are tied to positive behavior.
The “Holiday Nashor” Icon was given to players who showed positive behavior during Christmas season of 2012.
This icon was sent out to players who had no restrictions or bans on their accounts at the launch of the Instant Feedback System in 2015
The Honor System was introduced to League of Legends on October 1st, 2012.
It was created to incentivize positive behavior among the League of Legends community and identify Summoners that would consistently show positive behavior in their games.
It is a foundation that helps Riot identify positive players.
Previously, reports were the only way to measure whether a player is toxic or not.
Differentiating positive and neutral behavior was not possible this way.
The Honor System has received an overhaul in the Mid Season of 2017 to make Honor more meaningful..
Similarly to reporting a player for negative behavior, you can honor others at the result screen at the end of a match. By clicking on the “Thumbs up” button next to a summoner’s name, you will be given a choice out of three of the honor categories for allied players, or you may select “Honorable Opponent” when honoring enemy players. Honoring a player by selecting one of the options makes it impossible to report the same player for negative behavior. Inversely, reporting a player makes it impossible to honor that same player.
Players can only honor other players after a matchmade game
(including Co-op vs AI), as this feature is unavailable for Custom games.
Summoners who would be honored through this category are those that have a positive impact on your game and make the match enjoyable, regardless of victory or defeat.
This category is for summoners that share their know-how and actively help other players improve their gameplay.
Honorable Opponents are players from the opposing team that remain humble in victory or graceful in defeat and/or in a positive manner throughout the game. This is the only category where a player can receive a crest without any points in the other categories.
This category honors players that put the team ahead of themselves. This includes forming great strategies, helping struggling lanes recuperate, and much more.
The amount of honor a player can give is high, but not unlimited.
Players can run out of honor to give if they abuse the system by honoring players that didn’t behave sportsmanlike or if they try to farm honors by trading them with others. This is a reportable offense.
Honoring friends is completely acceptable and it is encouraged if the summoner in question is truly being a honorable player. In terms of unlocking crests, players will effectively be granted a different amount of honor depending on who honored them. For instance, a honor given by a stranger in a matchmade game will count more towards a crest than one that was given by a friend that they queued up with, even though the counter goes up by one in both cases.
The most honorable players in the community receive crests as a reward for their behavior. They will be visible in the Champion select and in the Loading screen.
For a player to receive a crest, they must be consistently honored in the appropriate category or categories. Riot did not publish specific numbers needed.
The total amount of honors a player received does not contribute to earning a crest, this is a common misconception. 
When a player has received enough honor in the appropriate categories to earn such a crest, they will be presented with an animation in the client and a message congratulating them on their achievement.
For Honorable Opponent, this is achieved by consistently being honored in the “Honorable Opponent” category. For the remaining three crests, a combination of the honor categories must be achieved.
There are four crests: Great Leader (yellow), Great Mentor (blue), Great Teammate (green) and Honorable Opponent (red). Honorable Opponent is the only one that appears visible for the enemy team. All crests are visible to spectators.
Below you can see the notification a player will see once they have unlocked a crest.
Only a single crest will be displayed at a time, even if a player has unlocked more than one crest. The crest displayed will be the rarest out of those that the player has unlocked.They are visible to other players during champion select and on the loading screen, where it will be placed on the top of a Champion’s splashart.
Crests are temporary rewards. They can be lost if a player stops acting positively and no longer receives honor. Being punished by the tribunal will also remove all crests and honor points from a player’s profile.
While 250% more honors than reports are given, Players wearing crests are rarely seen, because the majority of them mostly plays Co-op vs. Bots and ARAM games.
Meeting a player wearing one of the crests means that you will likely play a good game with no complaints, as honorable players are directly linked to positive games .
Riot wants to revisit and improve the honor system in the future, but there currently is no specific information on the planned changes.
The goals of these changes are the following:
Shortly after the release of the honor system, Riot have released following statistics about the changes in reports in normal and ranked queues:
Together with reports, honor is used to set the behavior standards of the community.
As players honor & reports certain behavior, the system will learn what behavior it should punish or accept. 
You can see your Honor, separated into the four categories, on your summoner profile. Honor is displayed directly above your stats overview and shows each category’s individual values. This bar is visible to all players that view your profile, and you can see other’s honor as well by visiting their summoner profile.
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