From the publisher's website:
“Everything out there is trying to kill you, soldier. If you figure that out quickly enough, you might live long enough to pass it on to the next batch of fresh casualties-to-be.”
–Private Mercito Grant
Across the Spinward Front, Imperial Guard troopers contend with deadly adversaries, from the fanatical rebels of the Severan Dominate to the vicious Orks of Waaagh! Grimtoof, and from the insidious forces of the Dark Eldar to the profane minions of Chaos. Your mission may place you toe-to-toe with the worst the galaxy has to offer. Will you be prepared?
Enemies of the Imperium, a supplement for Only War, gives deeper insight into the deadly foes of the Imperial Guard who lurk in the Spinward Front. Enemies of the Imperium not only contains NPC profiles and guidance on how to deploy them in battle, but it also provides considerable information on how these factions make war on the Imperium and each other. Further, Enemies of the Imperium provides rules for managing Formations to facilitate squad-level combat and new resources for Guardsmen and Support Specialist characters who have cut their teeth against these deadly foes, surviving the worst that the Spinward Front can throw at them.