We all know it. You can do almost anything in game - troll, change lanes even if you got other role originally, don't help teammates, ignore teamfights nearby you, just farm silently while others are killed near you.
Just pretend you're stupid :) NOTHING will happen. You have to be REALLY extreme, and do it EVERY game, LOTS of games until you finally get punished in any way. Everyone's entitled to have a bad day sometimes, right? ;D
But try using a swearword at such troll. He silently troll until you lose. Then report you. You will get punished right away :)
Yes, bend over and let them troll. Hope they will not get in your team next game. Bend over every time. Ignore what they do. Just lose. Just waste another hour of your life. You know they will get away. Oh you lost temper for them trolling? Called them a name. Yeah, get banned.
Intentionally trolling is not forbidden. I was jungle last game. ADC got smite, stole my blue at start, kept trolling, stealing jungle, laughing at me. He finished 0-10-2.
I reported him. Nothing happened.
Guess how long it takes for you to get punished, if you call such troll a %%%%%% : ) Yes, next game you have a ban. And they can troll away.
Bad word is much worse than intentionally wasting an hour of 4 people's life :)