Mute mastery flashes, pings and chat.
I honestly think its fine for mastery flashes to be seen by the friendly team, however when the enemy team can see it just becomes toxic behavior. "look at me i'm a mastery 7 (insert champion) i know how to press R and right click." Then they start flashing it for the tiniest reason and it does get really tilting. I think being able to mute someone on the team or enemy team should also mute mastery flashes. Same goes for team members. As for pings its annoying when you get that one troll who spam pings. Then you mute them so they spend the rest of the game MIA pinging you. "But even if you mute them they can still ping you about MIA enemies and communicate that way!" In all of my time playing i have never experienced this. "you shouldnt be tilted over mastery flashing loser" neither should someone be tilted by chat or ping spamming but it happens.