Under the Sign of Saturn

The Host of Traitors led by Horus Lupercal is tightening its grip on the Imperial Palace. The walls and towers begin to buckle and collapse one after another. Rogal Dorn, the Praetorian of Terra, doubles his efforts to hold back the relentless enemy, but the defenders have far fewer people and are catastrophically lacking firepower. Dorn simply cannot defend everything at once. Now any attempt to survive requires sacrifices, but which battles will Rogal dare to lose in order to succeed in others? Is there a possible tactical move, a decisive battle that could forever change the course of the war and bring victory to the defenders?