There are dozens and dozens of bugs/glitches associated with this boss and Arah path, but this one should at least take minimal effort to fix.
She is supposed to begin her daggerstorm attack after returning to the center. This sometimes happens instead: http://www.twitch.tv/purpleishawt/c/3958251
Please fix, unless you plan to tremendously nerf the damage that each orb hits or make them reflectable lol. Else it’s illogical to enable her to begin the daggerstorm here.