Shadow AOE is in a really weird spot. IT CAN be very good, but it’s generally not. IT also falls off significantly in a kiting meta as mobs get strung out and searing nightmare won’t hit them all.
You have to commit several talentsto it or it’s the wrost AOE damage in the game for any dps class. Searing Nightmare is good, but why do we have to talent for it just to do the same AOE damage or less than classes as their baseline abilities? It’s really dumb that this is a talent and not just baseline for us.
We also have to use shadow crash. We also have to use surrender to madness for the extra void forms. These are all mandatory talents to up our trash damage in mythic+. The only time you use misery is maybe in theater of pain because of the first boss fight and the fact most of the trash are smaller pulls.
There are a few niche scenarios where searing nightmare is god tier. Like the slimes in PF. But that’s just one example, and there aren’t too many others, other than maybe a few spots in DE other Side.
All in all, shadow priest aoe damage is very finicky and the fact of the matter is, it’s just not worth it to bring a shadow on keys over 12 with how tightly tuned the content is.
There is one comp that can run a shadow priest at a high level. Only one. And it relies on twins of the sun priestess legendary with a unholy DK in the party. This comp is DH tank, Unholy DK, Shadow Priest, Mage, Paladin Healer(but you can opt for a shaman or resto druid as well).
But at the same time, this comp is probably better off dropping the shadow priest and bringing in a boomy and possibly replacing the DK with a WW monk.