Mastery spamming IS griefing
I don't understand why Riot added the mastery emote. It's one and only purpose is to rub it in the face of someone you just killed. The game is already frustrating enough, when you die you don't need to see the enemy cheerleading over your corpse. It's completely meant in a negative way because anyone with respect or honor wouldn't do such a thing. So Riot why would you add a feature like this to the game that already seethes toxicity?
If you insist on having them in game why don't you make it so only your teammates can see it, like the mastery flag flair stuff on the loading screen. Your teammates can see it, but you can't see the enemy mastery banner.
At the very least, give players the option to turn mastery emotes off.
