This bug happens on the delve story where the end boss is split into two phases with the speaker and the shadow elemental.
The shadow cone frontal of the speaker appears to be 30 to 45°, but in fact it is 90°, range also appears to be bigger than it looks like.
Just useless dying here because the devs are not able match visuals with damage areas.
Blizzard should update the visual of the frontal so that is matches the size of real effect.