In another universe, humanity lies under siege by the forces of chaos. With millions dead and the heroes unable to stem the tide, things begin to look bleak. However, the battle soon draws his Majesty's attention, thanks to the presence of one of His faithful. With it, he sends his forces to crush the servants of the Dark gods and answer his most faithful's prayers. Image not mine.

A massive Warp Portal appears above Earth and with it an Arbitrator who enters a Universe of Gods, Heroes, and Villains. The Imperium may have not existed yet in this time, but through him Its laws will be obeyed. Through Blood and Iron, he shall enact the Emperor's Justice whether the League or anyone else allows him or not. Judgement has come to those who come to harm Earth.