The Rank System.
It is absolute shit. It is the main reason for the shared opinion that this game is the most infuriating and unfair game ever. My rank depends on 4 random people that could be absolute kids staying up past their bedtimes, who think it's funny to be irritating. People trolling, intentionally trying to fuck over our LP, and there is no way to avoid it, because if you dodge, you lose LP, which is BS. Riot has created a terrible system that needs to be changed as soon as possible.