I've just been in a ranked game (that has been dodged by another player) and a player was just trolling from the start. I could go and look on it's LoLKing history and for at least 10 games he's been trolling every game.

Here's the communcation we had with him.

Kuleran joined the room.
Thomanix joined the room.
xDrayken joined the room.
nerdyman787 joined the room.
xDrayken: ?
pachoangman: hello my friends!
pachoangman: you have been selected for ana utomatica loss
pachoangman: i will troll you
pachoangman: i will feed
pachoangman: i will afk
Thomanix: lol
xDrayken: Seriously..
pachoangman: if you don't believe me check my match history!
xDrayken: I lose this I drop back silver 4 because of trolls like you
pachoangman: You lucky summoners have been selected for getting trolled!
pachoangman: welcome to elo hell my friends!
pachoangman: good luck!
nerdyman787: my god you are an *******
pachoangman: http://www.lolking.net/summoner/na/27804712#history
nerdyman787: how have you not gotten banned yet?
pachoangman: this message is not endorsed by riot games
pachoangman: cuz i get paid to troll
pachoangman: to keep you silvers down
pachoangman: we don't want people to climb
pachoangman: in the ranked system
pachoangman: i get free level 30 smurfs
xDrayken: I'd climb if kids like you didn't play this
nerdyman787: fking elitists...
pachoangman: to troll you guys
xDrayken: I'll support
pachoangman: riot gives me level 30 smurfs to troll on purpose to keep silvers down
pachoangman: http://www.lolking.net/summoner/na/27804712#history

So that begs the question, can you report without playing the game with the troll?

I've just been in a ranked game (that has been dodged by another player) and a player was just trolling from the start. I could go and look on it's LoLKing history and for at least 10 games he's been trolling every game.

That begs the question, can you report without playing the game with the troll?