Bring back Crystal Scar Map as a Team Deathmatch game.
I don't miss Dominion the game mode, but I do miss the map. I think if Crystal Scar was brought back as a "Team Deathmatch" mode, it would be very healthy for the community. It would greatly reduce toxicity. Why? Because the primary cause of toxicity and unfun games in League of Legends is that half the people on a team want to play the strategic elements of summoner's rift, and the other half just want see their personal kill score go as high as possible, regardless of teamwork. The crystal scar map is perfect for this, and it would give people who just want to ignore teamwork and run around and kill things a place to be, preventing them from spoiling the games of others who are in the mood for a serious strategic game.