You’re Either with Us, or You’re against Us.
Ever since the lines were drawn between law and chaos, a chief obstacle affecting both sides is the fact that outsiders have great difficulty killing each other due to their damage reduction. For instance, in the lower planes, units of bearded devils and vrocks can struggle for hours with no casualties on either side unless they are armed with holy weapons, which will harm the wielders in addition to their opponents. In the cases of the lower varieties, this can be overcome through special materials, so many of the smithies of the Pit are allocated to cold-forging, and demon expeditions using xorn slaves to hunt for silver in Terra are essential to the war effort. For bigger targets, mercenary assassins are in great demand. Many a bearded devil works in tandem with an erinyes inquisitrix who can root out those sneaky shape-shifting demons. This has led to demons sending more mortal infiltrators, as both sides use the likes of tieflings and humans, countered by allied night hags to detect those of inappropriately chaotic bent.
A Guide to Distinguishing Demons and Devils
As noted in the origins of demons, the two sets of fiends have many similar-looking creatures in their demographics. The most immediate difference is in their overall shape: bipedal devils even as low as imps stand proud with symmetrical features, whereas demons tend to be hunched and deformed by human standards. Demons also lack the consistent characteristics of devils (six limbs, spiny scales, horns). As an example, a particular vrock may have seven limbs, including wings that appear more like those of a bird than a bat due to their soft feathers (compared to the spines worn by devils).