By banning him you're only making him stronger each time. Kin's way would be to stop banning his accounts and let it be a well known fact who he is. Users will naturally stop feeding the troll and others will add him to their ignore list. Eventually his threads and posts will get minimal replies, he'll get so frustrated and bored that he'll finally go away. Give him no attention and he will cease to exist. All these threads only feed to his ego, making him stronger.