Morgana bug or exploit

Just played a rank game and was winning bot everything was normal until for some reason I was stuck. At first I thought it was lag but everything was moving fine and chat was not lagging. Then I realized it was morgana's dark binding it was invisible and how do you dodge something you can not see. She was not hitting many bindings then she was landing them all because no one could see them. About mid to late game you could just see a binding coming that kind of looked like purple smoke, I took some screenshots - For some reason the screenshots will not upload. Also when asked the guy he said something about using mlg. So if it is a bug could she be removed to she is fixed please and if it is an exploit should he not be banned for using it.