i've also had to deal with toxicity in my recent ranked game, at champion select this man, whom i'm not allowed to name, but i freaking wish i could, told me not to play yasuo since i had bad kda with him. i told him i didn't care and simply wanted to play the champion. nobody said anything. i ended up against riven mid being unable to do anything(because i'm melee and riven stuns then knocksup). i tried to limit my deaths to a maximum of 2 during the laning phase, and i had muted my entire team when i got in game, never said a word during the whole 40ish minutes. ended up with a nice 2/11 score, with 0 ganks on my jungler's part because he didn't like me playing yasuo. at the end of the game, while i was busy reporting him(who played graves jg) and the adc who were rude to me, i notice them writing ''Please report yasuo! Toxic and flamed during the entire game'' on graves part and ''yeah report that stupid kid'' on our adc's side, along with the nice support ''report plz''
TL:DR people are assholes, so dodge the game as soon as you detect one or waste a beautiful 30ish minutes of your life.