Make users sign a honor code to enable chat
And I don't mean just clicking "I agree" to the summoner code, as anyone can do that and not feel a thing. Although agreeing to the summoner code is also important, I think we need to add something more to prevent trolling raging and griefing
I'm proposing a system where you can choose to enable or disable chat. You don't have to sign anything if you disable chat, but if you click to enable chat, everyday, you have to type "I, (summoner name), promise to not rage, grief or harass other players." Believe it or not, typing that out makes people watch their behavior. There is actually proof that honor codes actually work in preventing bad behavior. Caltech has honor code take-home tests and they seem to be working just fine, at least, there is no news of getting rid of them, so it seems to work.
Also, when reporting people make a similar thing where you have to type out "I promise this is a legit report and not a false report... etc"