Umm, so, like, how does a boomkin even go about contemplating the downfall of a shadow priest? Many people I've spoken with seem to think that it's possible, even easily doable if one is skilled enough, but I cannot for the life of me even fathom how this is done, given our toolset.
They seem to have a counter for almost every trick up our sleeve. Between chain fears, silences, flash heals that can bring them from 20% to 70% in a few casts, and then a damage immunity to boot, just in case you manage to line up everything nicely to throw in their faces. In all my 1v1 world pvp experience here so far in mop (and I've had quite a few already, pesky frostmourne allies >.>), spriests are the one class I regularly struggle with. Most battles end in either one of us running away, mostly me though, but also a fair few times the spriest, and of those where there's a victor, it's, well, not me often enough xD.
What I currently do is
1) Stay the hell out of melee range (I save typhoon for when he manages to close the gap between us. I've tried saving this instead for his flash heal spam, but I find the gcd it costs me to make it not worth using, as he just suffers a knockback and then resumes his healing about a gcd later too.
2) Nature's grasp when his fiend appears.
3) Solar beam + Vortex when he starts to hard cast mind blast. If I don't do this and try to save beam for something else, I don't last very long :(. Entangling roots when he gets pulled back into the beam, and I use that brief period of him being silenced to top myself off and throw up some hots.
4) Moonfire/Sunfire spam for the most part. When I stop to hardcast he comes in and pops his fear.
5) When I get low I pop stampeding roar, run the hell away, and spam insat rejuvs to heal myself. I typically also use astral communion during this period to get me to whatever Eclipse is closest.
6) Pop cds after his first Silence. I think it might be best to pop them after he's used his defensives instead, but I find that if i don't use them, he doesn't get low enough to need to use his defensives =/