I know people get higher Low Priority Queue times the more they AFK, but at what point does that cap out? At what point does the player that does it consistently (every other game) get a 14 day suspension or perm ban?
anyone?
The punishment for AFKing is a low priority queue - after leaving too many games within a certain amount of games, there is a 5 minute timer before a player gets into the actual queue, which increases to 20 minutes minutes after reaching the next tier. This timer lasts for 5 games and resets after continued leaves. It has been many years since AFKing resulted in suspensions or bans (since leaverbuster was implemented).
There is no defined point where AFKing/leaving games bans you. The maximum punishment is a 20 minute low priority que for 5 games. The only way you'll get banned for it is if someone at Riot manually reviews you.
