boosting kalista

there was a kalista in my most recent game that admitted to smurfing at the end of game screen and if you check there match history they have 5 losses in a row then all the sudden 15 wins in a row when they switched champs. this is obviously either someone boosting or someone smurfing and trying to keep low elo (hence the losses https://ibb.co/n8sHTa https://ibb.co/h5P8ZF https://ibb.co/gMQFEF