In-game graphics showing incorrectly and client not responding

Today I have been doing a couple of games of League of Legends and some weird stuff happened to me. It all began when I entered a game and there was this Thresh with a skin. Huge thick lines were going across my screen and it was coming from Thresh's character, moving along with how he moved. Then I got myself into another game in which I tried to type something right after I died and my game including the rest of my pc, seemed to be freezing (whilsts I still heard the music and sound effects of players engaging on the background). I decided to restart my pc and quickly hop back in the game.

The weird part is that my PC is build of quite high end hardware. I guess I will lower the graphics for now and see what will happen. Please let me know if this issue is a common one or if it is a rare thing only happening to just me.