This issue was not really covered in the WoW Wikipedia, so I'd like to ask if anyone can clear something.
Shadowform and Darkness add a total of 25% to shadow spells and effects. However, does bonus damage (such as granted by items) gain that percentage of damage, or is bonus damage applied after the new damage has been calculated?
If I pretend damage calculation was exact, and I had 100 +damage, and a spell that hit for 100 Shadow Damage, then would my final damage be 250 or 225?