Load up checkpoint Bravo on normal or higher. Grab the target locator on the left side of the tunnel. After picking it up go outside when the bulkhead opens and move up the hill to the left. You’ll see two Wraiths come in at the base of the hill, one from the left and one from the right. Aim at the middle of the path between them, just before the spot where the warthog gets destroyed, and fire before they reach it so that they arrive as the destruction is raining down. If you miss just reload the checkpoint.