User blog comment:Willbachbakal/(Champion Rework) Graves, the Outlaw/@comment-24385282-20150212221426/@comment-1330314-20150212233638

What it says on the tin. :P

Basically, I think the smoke should act a bit like brush in that it obscures vision of anything behind it. If there's nobody around except you and an enemy Graves, and there's a smoke screen between you two, you wouldn't be able to see him.