Report for taking line of other player

Support: I am going to take mid. Mid: I am mid. Support: No, I am going mid. ...

How often have you seen that? Even in ranked? Then the legitimate MID can either play support (which gives a chance for a good game but is just unfair) or the game is trolled and quite likely lost - two mids competing with each other aren't a good option in most cases. But, even if the game is won, it is just toxic. Yet, there is no report cathegory for that.