Report cards for all to see. Summoner Honor score
There are a bunch of different categories to get reported under. Would seeing your reports rack up help, hurt or be meaningless? Would you play with someone regardless of what their summoner score? I personally am fine with a system that makes trolls continuously make new accounts, get to thirty with 16 champs just to troll. You group up with someone and you see they have 52 (100) score, you know that it might not be a good idea to play with that guy. The only way to build that back up is to get honors, usually twice as many to offset.
By itself, the honors doesn't really mean anything. I got the honorable opponent banner and it went away within a few months. I have 387 under teamwork and 237 for honorable opponent. Maybe my Summoner Honor score is whopping 96 (not a percentile). It might mean I get reported in less than 3% of games I play. Would it be cool if you saw that next to my name? If I had a bad game it is more than likely I got out played and that I wasn't trolling.
If trolls want to troll they have to go make a new account and build back. It would force him to play good sometime just to troll sometime. Now he got trolled... ironically.
No arguments about this system being being abused. There are easy ways to adjust for this.