Well, the only thing we can do about it is banning him every time possible. At least i will.

gonna duo with friend and play Graves+Nocturne now

Ok, it's possibly kinda obvious, but maybe for some of those suffering from those problems it will help.

Have you guys tried updating your drivers? Before you come at me with a 2 by 4 for treating you like idiots - I know it's very easy to do it once and forget about that for long months. And while it's not really a miraculous fix-it-all, I have run into enough graphical issues that were alleviated by updating to newest version of graphics drivers, that it may be worth a shot.

I am not in-game right now but just if you lower the effects quality (guess that's the name just lower em all)it will work if you did it already and it did not worked, you did it wrong; besides you can change the smokescreen somewhere in the particles files (i think) and make it not make everything black around you( but still make allies and enemies dissapear) just google how to modify the spells

Have lost about 5 games becouse of that smoke meanwhile. Ive read how people get RP and stuff for bugs they didnt even know exist and there is something that ****s up games singlehandedly for even some players with quadcore computers and i havent even heard riot aknowldges that.

Happens here too with Nocturne's ult and graves smoke granade . Kinda annoying specially vs Nocturne.

I have same problem but with kartush's ulti. When its casted my game starts to lag

This might help?
I have never experienced this bug we are discussing. Not even on my old computer but maybe the reason for that is that it always ran 4-30 fps anyway.