hmmm this is hard. three places to view their target must mean the three eyes of the Hive, and the bouncing back and forth must mean Shreiker seeker bolts. the "U-shaped conductor" seems like it could be the U-shaped path guardians stay on during the phogoth encounter. Is it Phogoth, by chance? Looking at it again, this riddle could also be referring to Atheon, as Supplicants and Vex enemies bounce back and forth between the three areas (past,present,future). So I will guess Atheon as well.