RAT FB - Presidium.png|Beginning of the end RAT FB - Citadel Tower Maintenance Shaft.png|Take lengthy detours RAT FB - Citadel Tower Exhaust Plain.png|Exhaust incoming enemies RAT FB - Citadel Tower Exterior Defense Grid.png|Beat Citadel defenses Citadel ME1 SLI - Tower.png|Back to the beginning You have followed Saren to the Citadel. He is trying to transfer control of the station to Sovereign so the Reaper invasion can begin. You must stop him and find a way to destroy Sovereign once and for all.