In my personal experience 99% of toxic players get to be toxic without any form of punishment.
They do get punished but there's nothing you can do once they're in the game with you.
When my team is losing the other team would call me out and talk trash and on my team there's always that one guy.
Turn off all chat, they usually have nothing good to say anyways.
muting will not help and I feel my patience running out. Slowly turning into a toxic player myself :/
It will don't be one of those "If he says an obnoxious comment, than I have the right to respond" ~Teemo from the video.
Just chill for a moment, watch funny videos, go outside for a bit. Fresh air works wonders for you, and helps you find a little bit of peace.
https://youtu.be/iXiAayQ8KRA?t=2m3s
If you're wondering where I got that quote... xD