I've been using items with +%physical skill damage on my babrarian and +%fire skill damage on my monk and DH. How exactly are these calculated? Do they stack additively or multiplicatively with +specific skill damage (e.g. Hammer of the Ancients)? Do they stack additively or multiplicatively with +%damage (e.g. Battle Rage)?
I would do tests on my own, but I can't seem to get any of the free screen capture programs to work so that I can do tests.