Not from the perimeter at all, but from within. A Herald, come to put a stop to them. He can see who it is through his scope when focus turns back towards the light display, but no emotion registers beyond a slight rise in adrenaline.

Breathe. Line up the shot. He sees the smirk, the green glow--

And he takes a shot directly at the negative image's temple. He's grown reserved about taking life with the Legion, but he doubts a Herald will be put down so easily.

They'll need to take advantage of this surprise. Moments later, he fades from view entirely and takes to the air.