Hidden Ones’ Hood
This armor piece is found in Colcestre in Essexe.
Go to the marketplace at the center of the city.
You’ll find some explosive barrels here. Bring one to the nearby nook where you could throw it on the ground to create an opening.
You’ll reach a large room with parts that are submerged in water. The goal here is to check the side rooms for keys and sniping any locks that you see.
Reaching the side rooms can be done if you check out any openings above you or underwater.
Anyway, you’ll be able to unlock the door to the Camulodunum Bureau’s main room. This has the cloak and the codex page.