Originally Posted by
daywalker02
From light comes darkness and darkness comes light
I think the Diablo franchise explained it very well, at least the way I see it.
You need balance, humans were the offspring of a demon and an angel.
Angels were too rigid with their laws, were not helpful and demons, you would guess, were evil, twisted and manipulative.
There lurks darkness in the brightest light, and you can find light within the vast depth of darkness.
I would guess that Khadgar found the light side and human side of Medivh or a power that he
could draw from and defeat the avatar of Sargeras, the Demon titan lord that possessed Medivh.