Declassify Mission: Use Longshots and Boltoks only
Continue forth and exchange weapons if you want and replenish your ammo. Continue upstairs to find the Declassify mission skull. After activating it, go through the door. Cross the bridge for a bit and enemies will come to ambush you. Take cover and engage them. As you up the second ramp, more enemies will appear. Defeat them and take out the grappling hooks before more enemies climb up.
As you make your way through the rooftops, you'll encounter some flying locust creatures. They'll be moving about, making it hard to kill them with longshots. Use boltoks and anticipate their movements to hit them. Take out more grubs until a Reaver arrives. Use longshots to kill the riders and the Reaver from a safe distance.
After taking out the Reaver, you have to cross the plank to the next building. Before doing that, you should spot a COG tag skull along the way. Go up the ramp beside the plank and find the COG tag on the floor behind the vent.
S. Bishop, COL, Gerrenhalt
Continue to the next rooftop and take out the last set of grubs to complete the section.