Declassify Mission: Use Boomshields and Lancers only
Should you choose to activate the declassify mission, you'll have to complete the section using only boomshields and lancers. Head through the door and clear the first set of enemies ahead.
As you move forth, you should spot a COG tag skull. Check the ledge above it to find the section's COG tag.
Continue clearing the enemies until you reach a fiery tunnel. Take out the last remaining enemies to complete the section.