Voice Chat
So, 2 years ago Riot made a post saying they would be working on implementing voice chat into the game. Since then, I've seen nothing except in-party voice chat. In-party voice chat is nice, but it doesn't exactly accomplish what many were hoping for when asking for voice chat. There are ways to implement it without dealing with people you find unpleasant. For instance, having a mute feature or having it to where you can leave anytime or even better making it to where you have to have honor level 2 in order to use it. I find that voice chat would be very helpful as people are more likely to react to people speaking than little pings on the map. This is just my opinion, but I feel it reflects my experiences with league precisely.
Edit: Also, we can have it where you report based on voice chat and can receive voice chat/honor decrease based on the amount of bans specifically in the voice chat option. I'm aware that's not how it usually works but it could be a high volume to result in action.