It happend to me a couple of times, when im hit from his hits when he uses it im getting my vision “blinded” as well.
I think the trigger is that he activates it as he hits someone.
Anyway this is a really nasty bug, it should blind only mal because for the very least he gets a major buff unlike the other blinded people 
Hey Sleeser,
Thanks for the report! We’d love a replay and timestamp of the matches where your vision issues occurred. If possible, please send in your replays to our Heroes Bug Attachment Inbox.
Thank you,
~ Fizivix