My copied DK's blood boil spell on MoP PTR hits for about 1950 damage (per target, both diseases up).
Compared to the same DK on Live that is a lot weaker, and i even recall reading that Blizz said they significantly buffed Blood Boil's damage (related to PTR/Beta) - which is definitely not what i am seeing.
Can anyone explain what is going on with Blood Boil's damage, is it intentionally nerfed (has the buff been cancelled?) or is it just bugged?