These armies of darkness were once in the service of the legendary dark lords Varexes and Baltasar, but although many still serve the will of their late masters, many also serve Ix, the true god of death, or any sufficiently corrupted and evil high priests who have recruited them into their fiendish cults. They have been a scourge even since before the Cataclysm; indeed their masters’ lust for power was, in part, the cause of it all; and they have terrified, conquered and destroyed many a kingdom in their ghastly greed.
The army itself is a pitiless horde, driven by pitiless masters. Those that live are twisted into cruel mockeries of their former selves; those that die are resurrected in service as mindless, fearless rank-and-file soldiers, and the enemy is not spared the same treatment when killed or captured. The Legion is truly terrifying on the battlefield; with ever-growing ranks of the undead filling the front lines, terrifying monstrosities acting in support, and wicked priests wielding death magic, bringing low even the most mighty heroes with visions of horror and, in the end, utter destruction of the body and the soul- at least, those portions of body and soul that are not put directly to use.