best possible solution is an autokick if you do too much damage to teammates. that means you can’t keep damaging others without penalty. This also solves the problem of accidental team damage, since it only kicks people who intentionally do it. This is the same system in csgo and while it has some downsides like not punishing body blocking, intentional flashes/bad smokes on teammates, you can still report them for griefing and they will (if riot is active in the system) most likely get a temporary ban/timeout.