I still believe Edda's fall into the dark arts was at the very least nudged on by an Ascian, as it just seemed such a flip from when we last saw her, promising to return to her hometown and concentrate on being a better healer (her lack of aptitude in Conjury is after all what cost Avare his life in the first place), to summoning voidsent and going completely insane (and such a thing is well and truly within the Ascians MO). But then, grief can really make you lose all sense of reality if have no one else to turn to or help you.