The Kabal of Lost Souls is composed almost entirely of Commorragh ('Dark') Eldar, and shares all their characteristics. Compared to humans they are tall and thin, move with considerable speed and agility, and have life-spans measured in centuries, if not more. Many Commorragh Eldar show some signs of the unnatural means they use to prolong their lives, including ghostly-pale skin, yellow or (in more extreme cases) red-tainted eyes, and in some cases produce auras of psychic disharmony much like a human Pariah (ref: Culexus Temple, Officio Assassinorum). It is worthy of note that several members of the Kabal's higher ranks do not share these characteristics, for a variety of reasons.
The Kabal's sole Archon, called Nemesis, is not Eldar, though she has much in common with them. Her body is human in its proportions, but through training or natural talent she has the speed and skill equivalent to the higher members of Commorragh's elite. She has unnaturally heightened senses, bordering on omniscience of her physical surroundings, which is a considerable benefit in combat. The workings of her mind/soul are anathema to psykers, and no telepath has yet made contact with her soul, in battle or otherwise, and retained his sanity.
The Lost Souls, as with all Dark Eldar, dwell in the realm called Commorragh (old high Eldar: 'fortress'). If this is a planet in the normal sense, it has never been located in the galaxy. Access to and from Commorragh is achieved solely by use of the Eldar Webway, and there is some evidence that Commorragh exists within it, or in some sub-set of it. Its physical dimensions are known to exist in a considerable state of flux, such that universal constants such as gravity and relativity are inconsistent at best. Notably, though some areas of Commorragh lie under a blood-red twilight sky, others extend in all directions, up and down as well as laterally, in a seemingly infinite expanse of hive-like structures. The exact dimensions of Commorragh may not be able to be plotted.
Each Kabal of Commorragh controls an area within which its rulers' words are law. The Lost Souls dwell within a structure they call the Ice Palace, a towering edifice of white crystal quite unlike the prevailing architectural style of the rest of the city/realm. For a short while after its emergence, the Kabal operated from a traditional power base, a section of the city known as the Cathedral, but through some indeterminate means this area was replaced by the massive Palace. In Commorragh it is not notably rare for buildings to twist in and out of the physical dimensions, but an alteration the size of the Ice Palace is unusual, and indicates considerable power of whatever sort allows such things to occur at all.
The interior of the Ice Palace is a microcosm of Commorragh itself. The Palace contains massive prisoner facilities, Wych arenas and training zones, laboratories and hospital-dungeons to accommodate Haemonculi, forges to supply weaponry and vehicles, and subterranean catacombs that defy traditional navigation, and seem to reach through much of Commorragh, to the dismay of other Lords. Expeditions to back-track along the twisting passageways that are known to connect to the Ice Palace have rarely returned, and never succeeded.
The first encounter between Imperial forces and the Kabal of Lost Souls took place in the year 943.M41 at Coriana. Archon Nemesis commanded a battleship that ambushed an Imperial Navy task force in orbit, while her forces closed on the Imperial Guard force that had just landed on the surface. Unable to manoeuvre due to their proximity to Coriana's gravity well, the Imperial fleet suffered heavy damage and was unable to land reinforcements for the outnumbered Guard. Unexpected assistance from the Adepta Sororitas Amazon Order drove Nemesis' battleship away, while cruisers from the Astartes Furies fleet rescued much of the Imperial army from the surface.
At this time Nemesis had only recently assumed command of the Kabal, which was still very much as it had been in its previous incarnation, the Kabal of Lament under Archon Carrecuana. Subsequent to this attack Nemesis rebuilt the Kabal more to her liking. It was at this time that the Ice Palace first appeared, the Kabal's long-standing alliances with various Wych Cults and Haemonculi Cadres were disrupted, and the battleship (dubbed 'Warchild' by Imperial forces) was discarded in favour of sole use of the Webway as a means of travel.
The Lost Souls operate inefficiently as an army, but this appears to be by design rather than necessity. The Kabal is organised solely by Nemesis' command, and as she is nothing if not capricious the demands of sound strategy tend to be overlooked by her servants in favour of satisfying whatever whim she seems to be currently indulging. Certainly, somewhere within the Ice Palace, there are forges capable of producing every variety of weapon known to Commorragh Eldar science, and training facilities suitable to keep the elite Wyches and Incubi at peak condition. Yet, for whatever reason, Nemesis chooses to ignore the potential of the power at her disposal, and fields forces equipped only well enough to achieve her goal of the moment, whatever it may be.
At their most powerful the Lost Souls come close to being unstoppable. In the few major engagements that Nemesis has entered into - generally against rival Kabals - she has wielded such crushing force that the enemy tends to be crippled before it can even begin to retaliate. For whatever reason, though, Nemesis appears to have no design on ultimate rulership of Commorragh. Battles involving her Kabal tend to be either complete routs for the opposition, in cases where Nemesis has some other aim in mind beyond combat, or terrible slaughters on both sides. In such cases, Nemesis seems to take some sort of pleasure in balancing her forces as evenly as possible against their opposition, and letting chance decide the outcome.
The Ice Palace contains the necessary forges and technical specialists to manufacture whatever equipment Nemesis desires. Aside from the standards of Commorragh forces, Raiders, splinter rifles and so on, the Lost Souls tend towards esoteric equipment, particularly as wargear for the various Dracons and Sybarites who lead the Kabal's armies. Unique weaponry, custom-designed for its wielder, is not uncommon.
The pinnacle of the Kabal's technology, and arguably the equal of any war machine the rest of Commorragh can produce, is the Harvester super-destroyer. The Lost Souls are the first Kabal recorded to field the vehicle in combat, and are thought to have designed it based on earlier, smaller prototypes created by other Kabals. Since its appearance, the Harvester design has been included in the forces of other Kabals. Some such vehicles are copies of the Lost Souls design, but it has been known for Nemesis to sell Harvesters, and other more exotic weaponry and equipment, in exchange for exorbitant prices in souls.
Imperial response to the Kabal of Lost Souls is divided, depending on the beliefs of the observer. Many Administratum officials agree, unknowingly, with the majority of the Lords of Commorragh, in concluding that Nemesis' failure to take over significant portions of the Dark Eldar realm indicates a lack of power, and that her occasional crushing victories in battle are the result of fortuitous circumstances. Others, particularly field agents, have a different view. Though the Administratum denies the possibility, and has been known to persecute those who state it, some insist that Nemesis could bring Commorragh to its knees if she wished to do so. They believe that, rather than seeking increased power as other Commorragh Lords do, Nemesis is instead simply amusing herself with some bizarre game, in which the lives of her troops count for little or nothing.
The society of Commorragh is known to be based largely on personal prowess at combat and politics, so those who rise to power are those who can bribe, blackmail, coerce and kill the most effectively. Within the Ice Palace the rules operate differently, to the dismay of Nemesis' many enemies. Nemesis herself cares little for politics, and as she seems to need nothing from the rest of Commorragh, is impossible to coerce. She respects combat prowess, sometimes, but has been known to murder skilful warriors without a second thought. At times she seems to admire courage, humility, self-sacrifice, ambition, and so on, but her moods are infinitely changeable, and any action she takes is no guarantee that she will do likewise in the future. On one recorded occasion she expended a force of over a thousand Warriors in order to kidnap a master Haemonculus, only to kill him several days later, supposedly because she did not like his appearance.
If there is a constant in the Ice Palace, it is that Nemesis favours the unique. She tends to get involved in the personalities of her subordinates, and those she finds interesting are showered with reward. What constitutes 'interesting' is open to debate, and bears no relation to what is most advisable or safest. On behalf of a menial slave she abducted, she has declared feud-warfare on the Kabal of the Black Heart, reportedly the most openly powerful in Commorragh since the demolition of the Kabal of the Crescent Moon during Nemesis' casual toppling of the Circle of Ten, formerly the acknowledged rulers of all Kabals. Many suspected that act to be a prelude to a Lost Souls seizure of total power, but Nemesis made no move to fill the power vacuum she had created. Again, it seems that she was simply displeased with the Circle, and removed them.
Under these conditions, bound to the whim of an Archon totally capricious, the lives of her subjects are unpredictable, and liable to be terminated at any moment for some perceived flaw in their character. Those who have prospered tend to be as mercurial as Nemesis herself is, in so far as they are slightly out of touch with reality, and pursue their personal goals with complete disregard for the consequences to themselves or others.