Do you want to know how to reduce toxic behavior?
Fix matchmaking.
90% of the time people are toxic because the skill level between players in the game is WAY OFF. I'm not talking about a little, I mean there is a colossal difference in skill level between players, leading to people being 0/10 , 10/0. Its not fun when you are 1/1 in your lane and a fed kha comes to gank you with 10 kills at 8 minutes and 1 shots you. Can you really blame people for getting pissed off?
fix your matchmaking, its honestly terrible. I'm not sure how a company as big as yours can fail so hard at one of the most important aspects of your game.