Gjallahorn first off does not "instantly kill" any strike boss. They are sponges, and gjallahorn isn't this magic weapon you claim it to be. During the nightfalls and weekly gjallahorn doesn't just destroy everything, unless it's solar burn which has only been the burn about a few times. Other than when it's solar burn you're an idiot if you use ghorn when any matched element heavy weapon will do tons more damage. Gets your facts straight.