If you play a custom league of legends game (hosted by you and passwords and such), but you are only playing with bots, will you get leavebusted if you leave that game? Sometimes I just want to have a 20 minute game for practice, but I would not like to get banned.
If you go to the support FAQ for leavebuster you can read:
I left a custom/tutorial game and I got a warning that my account may be temporarily suspended? I thought custom games didn't count?
They don't. This message will appear every time you leave a game, but custom and tutorial games will not earn you a Leaver Level. Leaverbuster only applies to games you have to queue up for = Normal, Ranked, Co-Op Vs AI, Dominion, etc.
So custom game does not count.