I save quelling for the deathdancers to help the tank snap aggro as sometimes he has a voice to manage as well, if your quelling has an impact on boss threat tables you just wasted your quelling before the part where aggro is actually difficult to handle. It's funny since so many of you just played the card of "well someone doesn't play their job right" while demonstrating how to waste CDs, and how to not effectively manage threat on T7.