A Rengar bola-like visual bug seen in the ROCCAT vs FNC match

Is this a visual bug or something? I had seen this in one of my custom games (as Rengar) but I didn't bother about it. And now with a match with no Rengar, this occurs randomly.

https://www.youtube.com/watch?v=JYsfuskqhU4

Bug is at 39:10.