I would like to suggest to change or remove the Mass Hysteria trait. It provides an exponential dmg increase together with the haste bonus of shadowform.
The exponential nature can be seen best in S2M.
This is an example of a high parsed shadow at Ursoc in 7.1 (a 7.1 parse was used as you can see the exponential trend much more clearly).
But MH is not only a problem in S2M, which was nerved.
It's also a big problem in multi dot fights as the ramp-up effect of MH is multiplied by the number of mobs.
I think the recent hotfixes are there because of this issue, as SWP and VT are getting hit the hardest.
I'm just sad to get nerved every content patch as they are unable to handle the scaling of MH.
Therefore it should be removed and the class should be balanced around that new status.
And yes, Mass Hysteria is going to always be difficult to balance due to the nature of it.
Blizzards balance team dropped the ball this expansion pretty hard.
Shadow's niche is multi-dot/spread target damage. I don't understand why everyone just constantly moans about every single thing about shadow. Can't even have our niche now because its "too strong".
"nerfing mass hysteria basically makes mastery a useless stat, all the way down from its current position of best/equal best"
with the hotfix nerfs it is not. Besides that, Blizz can easily alter the values of mastery to bring it in line with the others again.
"using a spriest friendly encounter as proof, lmfao."
Ursoc was used as an example to show the exponential nature of the current state of void form caused by the MH+Haste buff. You can observe this in any fight, given there is an extended S2M period.
"Anyone who believes anything else is utterly clueless"
You should really learn the terms of a proper discussion.
My proposal wasn't to nerf shadow priest, but to remove MH as its scaling is too good. After that Blizz can rebalance shadow so i doesnt need to be changed all the time.