Raiders in Destiny 2 can be difficult on their own, but the added challenges can seriously complicate encounters.
Destiny 2: Defenses Down VoTD Raid Challenge Guide
The "Defenses Down" challenge is part of the raid's larger challenge launch, which started on April 5th. This challenge changes the show meet significantly and now requires much more teamwork to complete.
This challenge only allows a single player to kill a protected Disciple's Hourglass Knight. Now you normally kill these knights with a special relic, the Darkness Laser, to extend the challenge timer.
However, to complete the challenge, you must jump over at least one of the knights and have the Darkness Laser switch places frequently between players. Good team communication is an absolute must here.