Leaver Buster is an automated system that Riot implemented to discourage players from leaving League of Legends matches.

• Leaving the game during champion selection:
  • Punishment (normal match):
    • 1st offense - Player is unable to join the matchmaking queue for 6 minutes.
    • 2nd and following offenses - Player is unable to join the matchmaking queue for 15 minutes.3 points
  • In addition to the above time penalties if the game was a ranked match, the player loses 3 League Points, for the first offense and 10LP for the second time before the timer reset.
  • This counter resets after 8 hours without leaving during champion select.
  • This counter is shared between normal and ranked.
• Leaving the game before the match is over:
  • The Leaver Buster system will automatically kick players who remain idle for 5 minutes.
  • Punishment (All): No XP/IP granted for the abandoned game
  • Punishment (Normal Match): A leave is added to the player's profile.
  • Punishment (Ranked Match): A loss is added to the player's profile. (Even if the players team wins)

If a game doesn't end (for example for server issues, or because every player left the match), no penalties are given out.

After receiving a certain number of leaves, which varies depending on the total number of games played and the distance in time between each leave, the player account gets first warned and then suspended for increasingly long periods of time, resulting in a permanent ban for re-iterated offenses.