How to fix trolling.
Everyone I've seen talk about this issue is divided. Some people say it's impossible to see who trolls, and the others say riot should find a way. To the people that say it's impossible, of course it will be impossible if nobody ever sees the problem as solvable. To the people who say it should be done, I'm fucking with you guys. It isn't our job to help rid LOL of trolls, it's riot's. So riot, you have to see this as a problem that can be solved. Don't listen to the people who say it's impossible, because for them that discussion ends right there.
My suggestion may not be good but it's here because I'm not one of those people who will tell you it's impossible. Make certain parameters for champions such that if a garen builds manamune, he gets caught for trolling. If a zed builds lich bane, bam detected. Lux with cleaver, detected. Just some examples but you get the idea. It won't be able to catch all the trolls and it's obviously only for ranked but it's a start. Riot can detect this automatically.