Declassify Mission: Finish before Reaver barrage in 2:30
Activating the declassify mission will have you clear the section within the time limit. The COG tag is located to the left side of the rooftops, behind some sandbags beside the stairs so if you're planning to maximize your time, I suggest starting the section without the declassify mission, get the COG tag and restart the section so you can concentrate on the declassify mission.
With the declassify mission on, open the door and grab the Booshka on the right ledge. Make your way to the right and kill ALL enemies in sight before the timer runs out. Depending on your enemy loadout, you may encounter Kantus priests or just the flying ticker-like locusts. Be aggressive but at the same time, make your shots count. Head to the launch point then press UP to finish the section.