Muting Champions
I remember a time when League of Legends was a little smaller. ARAM was a thing which you could only play in a custom game where everyone was on Summoner's Rift, bound by honor rules rather than a narrow map. Then Riot, listening to the outcries from fans, decided to implement a one lane, custom-game only map called The Proving Grounds. This was great for ARAM, but it also really brought to Riot's attention that players would spam emotes ( as in, jokes taunts and laughs ) to annoy the other players in the game. Therefore, Riot introduced the feature to mute a player, and the champion they're controlling would also be muted! This was an amazing addition! No more spending an entire ARAM hearing "your skills are inferior" because Master Yi set up a macro to taunt every time he moves.
Then, with the recent User Interface update, Riot seemingly removed this feature! Now I get players spamming their emotes all game and there's nothing that I can do about it, save for turning down all champion voices in the game... Hopefully Riot didn't intend to remove this feature, and maybe we can get it to come back? I hope so.