Instructions
Play the main single-player adventure through to the seventh memory of the second sequence, "Crepi il Lupo."
Kill all of the Followers of Romulus. This unlocks the first Romulus lair. Follow the new marker on your radar to find the entrance to the lair.
Approach the semi-circular tunnel entrance at the location indicated by the map marker and press the action button on your controller. You will enter the Romulus lair.
Follow the natural path of the lair to find the shrine entrance at the end. Kill any followers of Romulus you encounter on the way. Once you have killed the last one, the shrine door will open.
Enter the shrine and check all of the treasure chests. Take the scroll and key from the altar and exit from the shrine.
Check your map for black wolf's-head icons. These are the newly available lairs of Romulus.
Visit each one and repeat the process to enter the shrine to Romulus in each lair.
Check your map for a golden wolf's-head icon. This is the location of the Armor of Brutus. Use the keys you collected in each shrine to unlock the chamber that contains the armor.