I think I'm the only one who prefers the idea that Edda just went so mad after her experiences that she managed to find and cultivate these powers on her own. :-/

Reducing it to something lame like "Voidsent told her to do it." would just be incredibly cheap, uninspired, and would suck all of the intrigue out of this to me.

Rather tired of the voidsent as a whole honestly, but meh...