Again, text is straight off the Privateer Press Iron Kingdoms page …
The forces of Cryx exist solely to devour any and all things at the behest of the Dragonfather. Their martial strengths are speed, surprise, and force in numbers. Enemies of the undying know they must never be lax in their vigilance, for seemingly out of nowhere raiders can arrive without warning, carried across the sea aboard their infamous blackships.
Spreading like a cancer, Toruk’s agents constantly gather the dead of the battlefield. The Cryxian military is varied and powerful. More than once an apparently defeated Cryxian army has suddenly risen to snatch victory from its would-be vanquishers. These forces are made of blood-starved Satyxis reavers, degenerate mercenaries, and shambling thralls.
From the metal-rending fists of a mechanithrall to the filth-belching cannon of the bloat thrall, necrotechs have placed their stamp on everything that walks, crawls, or slithers out of their dank, macabre workshops. Supporting Toruk’s legions are the necrotechs’ black-iron masterpieces: shadow-forged bonejacks and helljacks. They are ultimate products of malignant intention and some of the most harrowing creations in the Cryxian arsenal.
While scouring western Immoren for its dead, Cryxian agents have specifically sought the bodies of arcane mechanics, innovaters, and strategic thinkers and stripped them of their secrets—questioning the dead is often easier than interrogating the living. What these forensic necromancers uncovered has bolstered their ‘jacks even more. They ascertained the make up of the arc node allowing warcasters to channel their potent magics through their warjacks. Effectively extending the range and battle potency of warcasters to devastating levels, this pilfered technology has augmented Cryx’s ‘jacks to even greater levels of malevolent destruction.
Stolen technology is indeed a Cryxian tradition. When the Orgoth were cast out of Drer Drakkerung by Toruk’s hordes, Cryxian warwitches and blackships soon began appearing in the Nightmare Empire based perfectly on the sorcerous designs of the erstwhile invaders. Of all the blackships, few are more infamous than the funereal galleon called the Atramentous, bathed in Toruk’s flames and manned by the ghastly undead Revenants.