After playing an extensive amount of Gragas, I noticed something very fishy going on with his "W" that I do not think riot intended..
In the event that a Gragas player gets CCed very close to or at the instance he uses is "W", by the time the animation has finished, his enhanced auto disappears. Literally. His next auto attack is just his regular old basic, with no bonus damage, and occasionally still keeps the animation the enhanced auto makes.
The reason I question this bug is simply that it makes a part of Gragas gameplay EXTREMELY "UNFUN". If I have to channel an ability that is quite a large part of my kit for 1 second, only to have someone HAPPEN to stun me right as I cast it, and then not be able to use it, is the most frustrating feeling as a Gragas player.
I do not believe Riot intended this interaction when creating Gragas as canceling this "w" requires you to CC him within an exceptionally brief period of time after he initially activates it. It doesn't seem humanly possible to react that quickly to an ability that isn't very vibrant in its appearance, and it almost seems random as to when it will actually get canceled.
It's not a very likely situation to experience, but when you've played as much Gragas as I have, you definitely start to pick up on it.
Hopefully there are some bright minds out there to let me know if I'm just dumb for not knowing that interaction, or if that seriously was not intentional.
I do not have a video clip to present at the moment but it would be very simple to recreate one.