Prior to build 9014, if you cast Shadow Word:Pain while using a trinket or some other damage boosting ability (as I mentioned with the old Dispersion mechanic), when you refreshed SW:P by casting Mind Flay (with the Pain and Suffering ability), your SW:P would carry that boosted/trinketed damage the entire fight, or until you manually refreshed it.
Build 9014 changed that. Now, when you refresh SW:P by manually casting it or by refreshing it with Mind Flay, the SW:P ticks are recalculated. So if you pop a trinket, cast SW:P, when the trinket wears off, the SW:P ticks will continue at their trinketed damage level until you cast Mind Flay.
This isn’t really a nerf, though – it’s a bug fix.
But that’s a hideous ‘bug’ fix! Nobody’s going to wait 18 seconds after a trinketed cast to use mind flay, which means you’re being cheated out of the full benefit of the cast. The spell’s coefficient spreads your spell power over its full duration – how is it fair if that then gets recalculated a few seconds in? I feel a stern word on the forums coming on…
Okay, I messed up on my wording somewhere in there.
While the trinket is active, your SW:P will have the trinketed damage. But after the trinket wears off, it will be recalculated with your next Mind Flay.
So, if you have a 20 second trinket and cast SW:P, for the first 20 seconds, SW:P will be ticking at the higher dmg. After that 20 seconds, when the trinket wears off, when you cast Mind Flay, it looks at your +spellpower, and refreshes SW:P accordingly.
Refreshing SW:P with Mind Flay won’t cut a trinket’s benefit short.