Hey there!
I've been playing disc priest for a couple of years, and I'm not the best player out there, but im average with just around 2,2k exp in both 2v2 and 3v3. One thing that kills me as a disc priest and really makes me struggle in arenas (sometimes even in duels), is necrotic stacking DK's.
As a disc priest, you rely on a fine mixture of healing and shielding with the various spells, however shielding does not remove the NS stack, and they can keep stacking to eternity and beyond. The 30% reduced cast time is hard to counter when you are shield based as well as healing, but can only remove it with your heals. When they stack NS and simultaneously dump loads of amounts of damage into you, or your teammates, disc becomes the by far hardest class to play against death knights in general. And if you do manage to save your trinket for say asphyxiate, and you survive, you will still be going defensive because of hard pressure (through peeling), and you will eventually oom and die. In the long run, because of the discipline mechanics you will not survive an average DK.
Now, the idea is as simple as this: If you have a 100k stacking NS on you, why would it not be possible to remove 75k of that NS with PWS, instantly removing the shield, and still suffer the 25k heal absorb and 30% reduced cast time? In my eyes this would be fair to disc priests, but since this probably won't happen, i just want an explanation why we haven't thought of this/gone through with it yet?
Sincerely, Nycto