Is it correct that this ability does not have a very clear counter? I've been running the Witch Doctor against teams that use VE, but even though it's very useful against their fury skill, grevious burns always stun other 2 or 3 characters on my team, including the Witch Doctor, which makes me think that your passive has a bug. That is, even if you use someone who can clean up your team, it is very likely that even this character will take stun. Placing immunity on it does not solve since the VE is also useful for removing such buffs.
Well, I guess it's no wonder most high ranks have spammed him absurdly.