I got 83 on my first try. I tried to remember characters via relationships, like "Lux > Garen > Jarvan > Swain > Leblanc > Veigar > Teemo > Tristana > Rumble > Heimerdinger > Corki > Blitzcrank > Viktor" and so forth. Thus, the characters that I missed were ones that really didn't have any notable relationships with anyone, like Malphite and Orianna.