I am sure there are positive people in this community. Yet, I have seen people do the most toxic/negative things ever without them even saying anything in chat.
Here is a list of some few:
Ping spam harrassment. (We've all seen it.)
Spam-champion-icon-on-Tab-menu harassment. (You know, when you click their picture repeatedly on the tab menu)
The question mark ping
The spamming-summoner-spell-cooldown
Here's a few that requires chat:
Asking for 9x report
Someone lying that you said something offensive in postchat or allchat (Recently had someone lie in postchat that I called him a n***** when I haven't said anything all game. I was mindblown.)
The usual bs they spew out at you
I've played this game ever since its early seasons (2-3), and it's been getting worse ever since. The retention rate of troll/toxic players and those who do not reform contribute to this. The rate of which new players join League and the chance of them being a toxic person also contributes. As I have discussed with my brother many times, "The IQ and attitude of this game's general playerbase has been dropping with each season."
Having a good game is great, but there are those games where people are the absolute worst and it's just very frustrating to deal with.
**You should also look at the fact that this game is a free game as well.