How does one go about reporting something like this, and can actually expect something to happen. Yea, he was being rude during the match, but this is what really gets under my skin. Please, handle these people.
Chat Records for the Champion Select screen are not kept for the Tribunal, and are not logged by Riot at all to my knowledge. If the player has said something especially offensive, you can copy/paste the chat into the comment section when reporting them post-game so that it will be visible to those reviewing the Tribunal case. Keep in mind though that, since it was copy/pasted, the credibility of it actually being said is questionable. Then again, you don't have much to lose from trying.
Personally speaking, I do take the above action into account when reviewing cases, especially if the logs run parallel to how the alleged player acted during game (via the logs actually visible to Tribunal), but I can't speak for everyone in the Tribunal.
Hope this helps at least a little. It really does suck that there aren't formal logs of the chat, but keep in mind that the in-game and out-of-game clients are separated (hence your computer opening up a new program at loading screen)
Here is how I handle it.
copy/paste the most offensive parts of the conversation. AS SOON AS you spawn into the rift, put into team chat...
"Tribunal: I am going to paste a few lines from starting game chat. Would another team member please verify that these things were said"
If you can get one other person to collaborate that what you put is real, it will not only deter the behavior, but if they don't straighten up, the tribunal has the ammo, and the backing they need to solve the problem.
90% of the time, the player reforms their behavior in the game, and I see no need to report them after.
Report him/her under verbal abuse and describe the way you got treated, I'm not 100% sure that they look at lobby chat, they should really include that in the reports thought if don't already, but just keep this in mind.
That's an awesome solution to get rid of these flamers! :D
its not just that, its also the trolls of league, i swear back a year ago i used to have fun with league but now that league is growing it is now LEAGUE OF TROLLS, it really pisses me off when i get a premade team of damn trolls 
or their is always at least one person who trolls the reason i left console gaming was because little kids always saying mad bro or just being irritating kids now i at least get a troll player 5 out of 6 matches :\ i wish i could 
them -_-
from my experience, tribunals dnt do shit.
Sometimes I just try to out troll the trolls. I had a game not to long ago where I was first pick but last pick said he was going mid no matter what. So I just picked Galio and played a duo mid with a support. The rest of the lobby got in on it and we had a vladimir go bottom to just be able to sustain, farm under turret, and hold the lane until we could rotate down. Our troll was a little mad lol.
