IFS doesn't beat trolls, but Riot Support can
My first ticket took 4 days to respond, so I didn't have much hopes of an early reply when I reported a player who held me hostage in champ select. I'm not sure if the player was punished or not, but I glady take Riot's word for it. He hasn't played in 2 days, so I hope that his account was punished.
Yeah, it sucks that the report system can't detect a lot of the troll cases, but that's why we have Riot Support. If you are a new player who got harassed by a guy who's dodging the system, try sending a ticket to Riot Support. With screenshots, of course.