What's the most tragically under used part of the shadow priest arsenal? Mind Sear, hands down.
Mind Sear, you see, is an old friend. It was a regular part of our rotation in Wrath heroics. When Cataclysm came, though, it suffered a significant nerf in power. You could argue the nerf was needed -- the game was changing, and the developers wanted us to approach heroics in a different way. Arguably, Mind Sear was a bit too powerful.
It seems that Blizzard may have nerfed Mind Sear just a little too much, however. It just received a buff in patch 4.0.6, and it's slated for another in patch 4.1. Did Blizzard go too far this time, though? Not far enough? And what does the buff mean for the way we approach heroics?