Can you leave aram custom game w/e ban?
Also, note that this goes for all custom games. ARAM or not, it does not matter.
As long as there is no kind of matchmaking involved, there is no penalty either. At least at this point in time.
© 2015 Riot Games, Inc. All rights reserved. Riot Games, League of Legends and PvP.net are trademarks, services marks, or registered trademarks of Riot Games, Inc.