I think it could be improved a lot by making the following changes:
- Searing nightmare generates up to 5 shadowy apparitions which deal damage and generate insanity. This would help with the fact that mind sear can’t generate enough insanity or damage in small packs.
- Make searing nightmare baseline.
- Replace misery with a talent that changes searing nightmare to apply no damage or shadows, but applies vampiric touch along with the shadow word pain it already applies. This would make psychic link and auspicious spirits more viable and massively cut down on ramp up time.
- For the talent where searing nightmare used to be, make it a talent where searing nightmare refreshes the duration of mind sear, so you don’t have to keep recasting mind sear or worrying about the GCD from searing nightmare delaying the mind sear cast.
Can see more about it in my post: My suggested Shadow Priest changes for 9.1.5