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Thousand Sons

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Thousand Sons


Legion Number XV
Primarch Magnus
Homeworld Prospero
Current Base Sortiarius
Chaos Affiliation Tzeentch
Colours Blue, yellow/gold
Specialty Psychic Warfare, Sorcerers
Battle Cry "All is dust!"

The Thousand Sons were the XV Legion of the original twenty Space Marine Legions. Their Primarch is Magnus, oft called Magnus the Red. The Legion turned traitor during the Horus Heresy, after which it relocated to Sortiarius, the Planet of Sorcerers, in the Eye of Terror, and dedicated itself to the Chaos God of change, sorcery and magic, Tzeentch. For a time it appeared that Tzeentch protected the Thousand Sons from the corruption and fragmentation that most of the other Traitor Legions underwent, but eventually the Legion went through a crisis of mutation and de-evolution, seemingly at the wish of their patron-God. Aghast at this development, their chief sorcerer, Ahriman, cast a powerful spell designed to render the Thousand Sons immune to the warping effects of Chaos. While the spell succeeded in this goal, it had an unforseen consequence of transforming the mutated Thousand Sons into little more than mystically animated suits of armour barely capable of being termed as anything more sentient than automata.[1]

With the only surviving cognisant members being those incredibly strong in heretical psychic powers, the Thousand Sons are now a legion of ghosts led by the damned.


The homeworld of the Thousand Sons was Prospero, a world populated by a small commune of outcast psykers.[1] Once a world of great beauty, it was attacked by Imperial forces utilising planet-busting weapons during the Battle of Prospero,[2a] with the result that it became a blasted ruin, declared Purgatus by the Inquisition.[1] Prospero would ultimately suffer the indignity of Imperial planetary bombardment a second time, ordered by the Inquisition in response to a large-scale gathering of Thousand Sons forces upon the planet as part of a sorcerous ritual. While the first bombardment (the one that took place during the first Battle of Prospero) ruined the planet's eco-system and tumbled all the works of both man and nature, it still left Prospero more-or-less recognisable. The second scoured the world with firestorms so intense that the surface of Prospero was turned into featureless black glass.[11a]


The Great Crusade

Symbol of the XV Legion pre-Magnus[38o]


A Thousand Son before the coming of Magnus

The Fifteenth Legion was formed on Terra, their gene-seed being created and implanted in the first legionaires during a brief resurgence of warp-storms within the boundaries of the Sol system itself. This brief warp-storm was said to have generated psychic flashpoints all across Terra's globe, resulting in outbreaks of madness, suicide and random violence. Whether it had any effect on the legion's gene-seed is doubtful, but upon learning of it years later Magnus himself considered it to be a poor omen.[3a]

At least part of the initial crop of legionaires – termed student-aspirants — were found amongst the population of the once geo-political entity known as the Achaemenid Empire. This area of Terra had been under the rule of the Emperor for at least a century at this point, and as a result had suffered little during the just-completed Wars of Unification. The Emperor himself, accompanied by a retinue of scientists, visited the region and had each and every family tested for compatibility with the Legion XV gene-seed. Those that were found suitable were taken to the gene-laboratories underneath the Himalayas to begin their transformation into Astartes. Present as one of these first student-aspirants was Ahzek Ahriman and his twin brother, Ohrmuzd.[3a] Upon completion of this process the Fifteenth Legion was used to quell what few pockets of isolated resistance to the Emperor's rule remained upon Terra, before being named the Thousand Sons by the Emperor himself and sent out into the galaxy as part of his Great Crusade.[3a] Their name is believed to originate from the first step of the Legion's creation process; for unknown (but presumably notable, if the Legion was named because of them) reasons, exactly one thousand Marines were created and trained first, with the Fifteenth brought up to full Legion numbers afterwards.[7] There only being one thousand Thousand Sons in existence at a point in time is a fact that, tragically, would repeat itself in the future on more than one occasion...

Combat Disposition and Record

The combat disposition of the Thousand Sons during the Great Crusade can be viewed in two distinct parts; before and after the discovery of Magnus.

The Early Crusade

At the beginning of the Crusade, they fought as tenacious and energetic expanders of the Imperium, and were not considered particularly distinct from the main body of the Legiones Astartes. Five years into the Crusade however, the warriors of the legion – much to their delight - all began to spontaneously develop psychic abilities. This development however, was followed by a wave of horrific, unwilling degenerative mutations. This mutative process became referred to as the flesh-change, and was much feared by the Thousand Sons after it first appeared during the Compliance of Bezant. Most of those afflicted were secured in stasis chambers in the hope that some future cure would be found for them, and the numbers of active Thousand Sons began to dwindle as a result.[3a]

Over the next several decades some of the then-discovered primarchs found the notion of psychic mutants being allowed to exist as part of the Emperor's Crusade distasteful at best and downright impossible at worst and began to variously move for their censure or spread rumours and condemnations about them. Chief amongst these detractors were Mortarion, Rogal Dorn and Corax. As the years passed, more and more of the Thousand Sons devolved into mutantcy, while those that survived grew stronger and stronger in the use of their powers. Meanwhile, the detractors had managed to raise enough voices to empower a proposal that the Fifteenth Legion be dispanded and expunged from Imperial records altogether.[3a]

Great Crusade era Thousand Sons Astartes

It was shortly after this that the Great Crusade arrived at Prospero and found Magnus, primarch of the Thousand Sons. The entire legion was transported to Prospero to meet their gene-sire, and there was much rejoicing even though the flesh-change had become a pandemic within their ranks. After the initial celebrations the Emperor and the main body of his fleet left Prospero, but the Thousand Sons remained behind, the numbers of them degenerating into mutantcy seeming to go completely out of control within a day of the Emperor's departure. Soon, the entire legion was afflicted. It was at this time that Magnus stepped in to save his gene-sons, enacting a mysterious procedure that was able to stabilise the genetic structure of the least-effected legionaires. At the end of the procedure, barely a thousand of the Thousand Sons lived.[3a]

The Thousand Sons on crusade[71]


With this stabilisation of the gene-seed, the Fifteenth Legion got its second chance. Recruiting from Prospero, they were able to rebuild their numbers – though would never become numerous – and return to the Great Crusade, this time led by their primarch.

While most details of how the Thousand Sons were organised before the coming of Magnus is not currently known, it is recorded that they were not considered particularly different from a typical Legiones Astartes apart from their psychic abilities (which resulted in the legion possessing the most powerful Librarians of the era[1a]). When Magnus took command, his directions (influenced by his development on Prospero, as well as Prosperine culture itself) would cause some organisational and hierarchial changes within the legion. Chapters were referred to as Fellowships within the Thousand Sons and the most of these the rebuilt legion was ever able to field numbered 10. However, at the conclusion of one particularly bloody campaign, the Thousand Sons had lost almost 900 Astartes, effectively wiping out an entire Fellowship. Rather than rebuild it, Magnus decided to reorganise and maintain the legion as one of 9 Fellowships, an organisation he referred to as the Pesedjet. Two special units were created within the legion; the elite Scarab Occult Terminators and the Hidden Ones of the Scout Auxillia. The legion's command structure was adapted to include Prosperine philosphy in the form of the Rehati (the coven of Magnus), a second command-track in which the legion's senior officers were ranked according to psychic ability and influence [3b]

The resurgent Thousand Sons brought their fair share of worlds into compliance with the Imperium of Man, and as such their main method of victory (diplomatic guile and trickery) was not questioned by the body Imperial. However, as the Crusade entered wilder regions of space, more and more hostile forces were encountered that deployed powers similar to those that the psychic warriors of the Thousand Sons wielded. This event, alongwith the ever-present rumours of 'witchcraft' and 'sorcery' surrounding the legion, resulted in Mortarion once more raising his voice in condemnation of the Thousand Sons.[1a] This time he was joined by Leman Russ, whose long-held distrust of the legion came to a head after he witnessed the return of the flesh-change in the Thousand Sons during a joint action on the world of Shrike.[3c] It was decided that Magnus and his legion would be called to account, and the whole matter of Astartes employing psychic powers at all would be ruled upon. This event was known as the Council of Nikea, and at it – after much deliberation – the Emperor announced that no Astartes must ever again employ the use of psychic powers, upon pain of destruction visited upon them by the Emperor himself.[3d]

Stunned, the Thousand Sons effectively withdrew from the Crusade, returning to Prospero. It was during the period that followed that Magnus discerned the approach of the Horus Heresy and employed both his own powers and that of his senior legionaires to try to save his brother's soul. Failing, he once again marshalled the powers available to him and attempted to psychically warn the Emperor of his favourite son's betrayal. News of this sanction fleet, meanwhile, had previously reached the ears of the now-corrupted Horus himself. Sensing an opportunity, the Warmaster contacted Leman Russ, commander of the fleet, during the trip to Prospero. Speaking with his brother, he was able to convince him that "to return Magnus to Terra would be a waste of time and effort". Horus confirmed to his traitorous council of war that he believed this interjection of his into the Emperor's own decree would result in Magnus never leaving Prospero alive.[31] This action, which went so catastrophically wrong, would doom the Thousand Sons as, in accord with the Judgement of Nikea, the Emperor visited destruction upon Magnus and the Thousand Sons in the form of Leman Russ and his Space Wolves.[1]

Magnus had realised his grave mistake in warning the Emperor in the method he chose, and had also been confronted with the stark reality that he was not as in control of the warp or his powers as he thought. Additionally, a power of the warp had spoken to him, revealing to him that Magnus had been its pawn since the time it had helped him save his legion from the flesh-change...and perhaps even long before that.
The Burning of Prospero
Distraught, Magnus resolved to accept whatever punishment the Emperor saw fit. Thus, to prevent his legion from defending Prospero he dispersed the Thousand Sons fleet from orbit, shut down the orbital defences and wrapped his homeworld in a 'psychic cocoon' which prevented anyone from communicating or using their powers beyond its boundaries. Thus the Space Wolves managed to attack Prospero completely by surprise. The Thousand Sons legionaires themselves, however, did not share Magnus' acceptance of defeat and punishment, and so took up arms against the invaders. The Thousand Sons managed to hold Tizca (the only surviving city on the planet) for a period of time before they were eventually pushed back, the assault of the Space Wolves led by their primarch, as well as forces from the Sisters of Silence and the Adeptus Custodes proving too much. Magnus eventually joined the battle when it appeared that the final moment of extermination for his legion had arrived. Leman Russ engaged Magnus in a devastating duel in which the Russ was ultimately victorious. In response Magnus finally, consciously gave in to the daemonic voice that had been tempting him and invoked ancient sorceries in order to escape Prospero with the remnants of his legion. In the Eye of Terror, a Daemon World had been prepared for them by their new patron.[3e]

The Horus Heresy

Thousand Sons symbol during the Heresy

Having been thus deliberately removed from the board by the machinations of Chaos,[2b] the Thousand Sons played no part in the birth of the Horus Heresy. In fact, exactly when and why they chose to ally themselves with Horus and his traitorous rebellion is not clear, although it is believed that their chief motivation was to gain sanctuary and protection from further Imperial attack.[6] Of course, considering how Tzeentch had orchestrated events so far, it is likely that they had little choice in the matter at all.[7]

After their escape from Prospero, the Thousand Sons discovered that – once again – they had been reduced to only around one thousand living members.[3j] However later, they were joined by at least 3,000 lost members of the Legion that were dispatched before the Burning of Prospero.[41a] The actions of the Thousand Sons' main faction during the bulk of the Heresy remained unclear, though a portion of the Legion did engage the Space Wolves at the Battle of Yarant.[34] Known records mention fragments of the XVth Legion active elsewhere in the galaxy during the latter years of the Horus Heresy, each one an independent warband rather than a strike force of a unified Legion. Loyalties proved split in such groups, with some fighting for the Warmaster and others siding with the Emperor, despite the censure he had brought down upon them.[79b] Notable self-proclaimed loyalist factions included the Fifth Fellowship under Sul Kontep which had escaped Prospero and would later align with the Imperial Fists;[38][79a] a group based on Zhao-Arkhad;[74] and the Thousand Sons of the 209th Expeditionary Fleet.[80]

The Thousand Sons' main faction ultimately discovered that Magnus had broken into Shards since his near-death on Prospero, and Ahriman and his Cabal devoted much of their time to discovering the shards and restoring their Primarch. Ultimately they were able to discover nearly all of the shards, but Magnus revealed that his remaining portion dwelt on Terra.[41b]

The Thousand Sons: Red Sorcerers of Prospero

Thus when Horus's forces fell on Terra itself some years later, Magnus and most of the Thousand Sons were with him. Noted to be a very small contingent of the Chaos forces, the Thousand Sons contented themselves with summoning daemonic reinforcements and casting supporting spells rather than engaging in pitched battle for most of the Siege of Terra. However, once the outer walls of the Imperial Palace had been breached, the Thousand Sons found themselves required to break down the final wards and fortifications of the inner palace itself. Advancing to the Ultimate Gate, part of the legion held off Imperial counter-attacks while the senior sorcerers attempted to destroy the defences with psychic power and sorcerous ritual. This assault came to naught however, as a contingent of Imperial Fists led by Rogal Dorn arrived in the combat zone and drove the Thousand Sons off at much the same time as the Emperor himself directed the surviving Librarians of the Blood Angels and Imperial Fists to block the attacks of the Thousand Sons sorcerers.[1] Later a group of Thousand Sons led by Magnus himself infiltrated the Palace to recover a lost shard, but after learning this was now beyond his reach the Crimson King changed the mission to instead slay the Emperor upon the Golden Throne.[50a] Thanks to the intervention of Vulkan, his Draaksward, and the pack of Bodvar Bjarki the attempt failed, and at the height of the battle Magnus fully gave himself over to the powers of chaos before vanishing from the Imperial Dungeon alongside his men. After the battle the Thousand Sons were fully committed to Horus' cause on Terra.[50b] Magnus next enacted a ritual in the Webway to sap the Emperor's strength and lower his anti-Daemonic psychic shield, but Vulkan journeyed into the realm to again do better with his brother as the Thousand Sons took part in the attack on the Eternity Gate. After Magnus' defeat at the hands of Vulkan, the Thousand Sons forces broke.[76]

The Thousand Sons retreated from Terra after the death of Horus alongside the other Chaos forces,[1] before using their sorcerous powers to open a warp route that would transport their fleet directly to the Planet of Sorcerers.[7]

Horus Heresy Aftermath

Dreadnought of the Thousand Sons[72]

The dedication to the Chaos God Tzeentch resulted in several changes to the organisation of the legion, but had little direct effect on their combat doctrine. Previously known to avoid close combat in favour of psychic trickery and the use of ranged weaponry, their development into a legion of Chaos Sorcerers and the effect of the Rubric of Ahriman only increased reliance on this approach. Those marines affected by the Rubric are used to anchor an attack's firepower, while the sorcerers deploy their psychic powers, the whole event orchestrated in accordance with a previously constructed plan of deceit or guile.[1] While showing no overt favouring of vehicles or heavy armour, the loyalist Thousand Sons did appear to deploy significant Legio Cybernetica assets in battle, although, in a fore-echo of what would come to pass with the use of Rubric Marines, they psychically controlled the robots to act as a mobile bulwark, rather than letting them operate as normal.[3h] The transition into a Chaos Legion did little to change the Thousand Sons' lack of interest in vehicular or heavy armour support; the discipline of machinery is one that most Sorcerers apparently care little for...although now and again one will take enough of an interest to produce something unusual. The existing Legion stock of vehicles and equipment has rarely been remarked upon since the end of the Thousand Sons' Imperial loyalty (indeed, it is not actually known if the Legion managed to retain anything other than those Legionaries who were transported from Prospero to the Planet of Sorcerers), but it is known that they sometimes scavenge or steal such items during raids. However, as the Thousand Sons show markedly little interest in properly maintaining their traditional armoury, these repurposed goods never last long and certainly do not appear in large numbers.[7]

While they avoided dissolution as a legion for some time, the Thousand Sons now only seem to operate abroad as small warbands.[1] These warbands are said to seek out conglomerations of psykers, or traces of sorcerous techniques using artefacts known as Seer Stones. Whilst the plans of the Thousand Sons are never easy to discern, being chosen as Tzeentch's favoured agents results in the actions of their warbands being varied and often curious; by raiding a particular planet, location or killing even a single, specific individual, the manipulations of Tzeentch are furthered.[7] The most well-known of these warbands is the Prodigal Sons warband led by Ahriman.[9a]

The Rubric of Ahriman

Ouroboros symbol

With the embrace of Chaos, comes mutation. Once the Thousand Sons had retreated back to the Planet of Sorcerers within the Eye of Terror members of the legion began to suffer the flesh-change; horrendous physical mutations, their bodies and minds twisted in ways only Chaos can achieve. Although some dedicated Tzeentch worshippers saw these changes as a sign of their god’s favour, those of higher understanding knew better, and decided that the Thousand Sons' search for enlightenment and knowledge could not end in the dreaded transformations they would inevitably suffer. Ahriman, once Chief Librarian of the Legion, and second only to Magnus in power, united a conclave of his most trusted sorcerers, and together they cast a spell, known as the Rubric of Ahriman, of tremendous magnitude that would save the legion from the fate of mutation. The results were not what Ahriman expected...but he was satisfied with them none the less. The Thousand Sons were now safe from the taint of chaos, but at a terrible price. Those untouched by the flesh change had their psychic powers greatly strengthened, but those who had already mutated had their physical bodies reduced to dust and their animate spirits damned to live inside their armour forever. Most of the legion were therefore changed into Rubric Marines, little more than mindless automatons. When Magnus heard about the terrible failure, he banished Ahriman and his group from the Planet of the Sorcerers, and now they wander through the Eye of Terror and beyond, still pursuing magical knowledge and seeking arcane artifacts. Ahriman’s current goal is to enter the Black Library of the Eldar, and rumour has it that if he succeeds in his quest, his power will grow beyond imagination.[1]


After the destruction of Prospero at their hands, the Thousand Sons have been long time arch-enemies with the Space Wolves chapter. They have tried several times to uproot and destroy the Wolves, ranging from a full-scale invasion of the Space Wolves' homeworld of Fenris[12] to plots such as those spearheaded by the sorcerer Madox.[4][10]

A Chaos Sorcerer of the Thousand Sons[72]

This vendetta would have an irrevocable effect upon the legion. The Thousand Sons had largely retained their legion organisation and structure after the Heresy, even raising and maintaining a large body of mortal troops they referred to as Spireguard in an echo of the Crusade-era Imperial Army regiments of Prospero. However, the last known act of the Thousand Sons as a legion was the Battle of the Fang, in which Magnus committed almost all of their remaining assets. At that time, there were approximately 700 members of the Thousand Sons left (not including the coven of Ahriman).[12a] Their defeat resulted in the loss of several of the remaining senior legion members, several squads of Rubric Marines, much of their fleet, and nearly all of their mortal minions.[12]

Notable Engagements

See main article — List of Battles of the Thousand Sons

The Great Crusade

The Horus Heresy

Current deployments of the Thousand Sons[40b]

Post Heresy

The Post-Heresy Thousand Sons at war



Post-Heresy Thousand Sons

Magnus placed great emphasis on ensuring that legion officers could operate independently from him, going to lengths to ensure they were taught all that he believed they would need to succeed at command, including otherworldly skills. Before the Heresy the individual Thousand Sons squads were led not by established veteran warriors, but by those who showed the most psychic potential. These junior officers were also effectively apprenticed to more experienced officers for cult training. As a result of the emphasis on leaders having strong psychic ability, senior officers of the legion typically became considerably experienced in both typical battlefield combat and in the use of their powers.[1]

During the Great Crusade and Horus Heresy, Veterans of the Thousand Sons wore the Achean Pattern MkIV Power Armour with distinctive helmets and shoulder pads.[33] Achean Pattern Helmets and Shoulder Pads were a variant Mk IV ‘Maximus’ battle plate design of the Thousand Sons Legion during the Great Crusade and Horus Heresy. They were produced by the forges local to Prospero exclusively for this Legion and used often by Legion veterans.[73]

Always a numerically small legion, the Thousand Sons rarely ever took to the field in great numbers. They would normally operate in small detachments, whose leader could effectively hold much more independent authority than officers in comparable positions in other Legions. With the events following the Heresy, this habit has become more pronounced.[1]

Before the Heresy, the Thousand Sons operated several Fellowships roughly equivalent to Companies. While there were originally ten, after the events in the Kamenka Troika the legion was reorganised into nine Fellowships. Each Fellowship was led by a powerful Psyker.[3h] Spread out among these Fellowships were several Cults that specialized in different Psychic disciplines.[3i]

In addition to the Fellowships three Red Orders were also fielded by the Legion before the Heresy. These Orders were more devoted to military matters rather than psychic craft or knowledge. The three orders were the Order of Ruin, known as the Unmakers, which specialized in siegecraft and logistics. The second was the Order of the Jackal, known as the Measure of Life and Death, which operated the Legion's Dreadnoughts and Khenetai Occult. The third was the Order of Blindness, known as the Hidden Ones, which fell under the command of Amon and operated the Hidden Ones and Ammitara Occult of the Legion.[38a]

The Cults of the Thousand Sons

Cult icons of the Thousand Sons

Every legion venerated their primarch in some regard, but to the Thousand Sons Magnus was their literal saviour. With his arrival they were not only (apparently) saved from the horrors of physical degradation but also presented with the person who could teach them how to master their developing psychic abilities. Drawing from his experiences on Prospero, Magnus instituted his Cult system within his legion, five teaching institutions that would allow his warrior-scholars to expand their knowledge, principally from him, at his position as master of all the cults; the rank of Magus. From this position atop a pyramidal teaching structure, Magnus was able to direct and control his legion's psychic and philosophical development; as the most knowledgeable, powerful and as their genetic forefather and saviour, all Thousand Sons looked to him for example and guidance.[3f]

All members of the legion were cult members and outside their military rankings, would most likely associate with their fellow cult members in their own headquarters pyramids in Tizca. These cults, in tandem with Magnus' more direct teachings (like the invention of the Enumerations), promulgated the methods of control the Thousand Sons developed over their powers and came to be an essential factor of the marines' existences.[3f] The status of the formalized cult system after the Burning of Prospero is unknown.


While Magnus himself remains the ruler of the Planet of the Sorcerers, for a time he was increasingly aloof with the affairs of the Materium and is spending much of his attention waging the Great Game of the Ruinous Powers.[22a] Thus since the events of the Heresy the Thousand Sons largely operated as independent warbands under the control of Sorcerers.[1] However this all changed around the time of the Thirteenth Black Crusade when Magnus reasserted his rule over the Legion, reconciling and reforming it.[39]

The modern Thousand Sons are built around Nine Cults, each of which is overseen by a member of the Rehati, a coven of nine Exalted Sorcerers and Daemon Princes favored by Tzeentch that hold the rank of Magister Templi. The nine cults are currently:[40a]

  • The Cult of Change — The great unravellers, launching their armies wherever order, civilization, and reason exist. They seek to impose their will in areas where anarchy exists.
  • The Cult of Duplicity — Unique in that they both are and are not unified by a desire. Its Sorcerers are deceivers and it is unknown if they are acting independently or as part of a singular unifying plan.
  • The Cult of Knowledge — Seeks to uncover hidden knowledge particularly tomes of eldritch learnings, dark secrets, and paradoxical logic.
  • The Cult of Magic — Embraces pure sorcery and seek to obtain arcane objects across the Galaxy.
  • The Cult of Manipulation — Operating vast networks of spies, they oversee acts of mass manipulation to destabilize worlds and sway their enemies.
  • The Cult of Mutation — Embrace the warping of flesh and transforming planets into Daemon Worlds
  • The Cult of Prophecy — Prophets and soothsayers
  • The Cult of Scheming — Consists of master planners. Every action taken by this cult is a perfectly planned maneuver leading to a unseen master stroke.
  • The Cult of Time — They view the flow of time as an unwrought resource that can be shaped into a weapon. By their victories, ripples are sent both forwards and backwards in time, so that their enemies may be defeated before they are even engaged.

Each Cult in turn is divided into nine Sects commanded by lesser Sorcerers and Daemon Princes. These in turn are divided into Thrallbands, which make up the basic fighting units of the Thousand Sons.

At the core of the war assemblies of the Thousand Sons are the thrallbands. These primarily consist of a champion known as a Magister and up to nine thralls, each a lesser Sorcerer-champion of Tzeentch. This cabalistic gathering usually manifests as an Exalted Sorcerer and nine Aspiring Sorcerers – or Scarab Occult Sorcerers – who lead the Rubric Marines and Scarab Occult Terminators into battle. In the rarest thrallbands, the thralls might instead be powerful Sorcerers or Exalted Sorcerers themselves. The Exalted Sorcerers and Daemon Princes who rule the Silver Towers each command many of these thrallbands, which may be gathered together into hundreds-strong task forces called Exalted Thrallbands. Their followers comprise the raiding forces through which Tzeentch enacts some of his most violent schemes upon the galaxy. While the warbands of Tzeentch’s champions manifest in countless ways, the sorcerous thrallbands of the Thousand Sons are the most favored by the Changer of the Ways. Each thrallband is bolstered by the mutated warrior auxiliaries of the Planet of the Sorcerers, or by Chaos Cultist forces drawn from the Imperium. In addition, the Legion maintains a small number of tanks and Daemon Engines. Some Space Marine equipment is captured during their raids, but as very few of these weapons or vehicles are properly maintained, they rarely last for long and so are never numerous.[37]


A victim of the Flesh-Change[78]

Magnus was unquestionably the most profoundly mutated of the Emperor's Primarchs, both physically and psychically, and the Legion imprinted with his geneseed reflected that with a high percentage of Thousand Sons manifesting some level of psychic ability.[63] Unfortunately the legacy of Magnus also brought with it a curse; a debilitating flaw in the geneseed known to the Thousand Sons as the Flesh Change (also Flesh change, Flesh-change), a degeneration - sometimes sudden and extreme - into mindless, mutated, monstrosities. The Flesh change was not detected during the Legion's inception and early years on Terra and, indeed, did not manifest within the Thousand Sons until a little over 10 years into the Great Crusade, after a seeming mass-"awakening" of apparently dormant psychic abilities in the majority of the Legion.[38x] The Emperor, Malcador The Sigillite, and the Selenar gene-cult all expended much labor to isolate the flaw in the Thousand Sons' geneseed, but unfortunately Malcador and the Emperor concluded it was beyond their ability to cure, and it was hoped that reuniting the Legion with its Primarch would eliminate the flaw.[63]

The exact cause of the Flesh Change, and what triggered its onset, was not known. Malcador The Sigilite initially believed it was due to an error in the XVth's "gene encoding", a belief he clung to for many years before he and the Emperor ultimately realized they could not cure the Thousand Sons.[63] There may be a link with sustained, heavy, use of psychic powers, as the Thousand Sons fell en mass to the Flesh Change during the burning of Prospero, when the Thousand Sons desperately unleashed ever more powerful 'sorceries' at the Space Wolves and Custodes of the Censure Host to try and defeat them.[3] Another victim who fell under similar circumstances was Revuel Arvida, who continuously used his powers to assist the White Scars, during their campaigns against the Death Guard and other Traitor forces.[64] However, this may simply be correlation and not causation, as Thousand Sons legionaries who completely lacked psychic ability were just as susceptible to the Flesh Change.[38x]

Before the discovery of Prospero, and the Legion's reunification with Magnus, the Thousand Sons had attempted to hold the Flesh Change at bay with retro-virals, alchemy, meditative techniques, and sheer willpower, but all of these techniques eventually failed in time. Legionaries who became aware of the onset of the condition - or who had to be subdued by their brother legionaries when the change was sudden and overwhelming - were put into stasis, in the hopes a future cure could be found.[38x]

When the Flesh Change was a gradual onset, afflicted Legionaries could feel their flesh rebelling beneath their skin, and their appearance often took on a pallid, waxy, look. When the change took over suddenly, the results were immediate and spectacular - the flesh and blood of the legionary was in complete flux, with power armor shattering and mutating flesh spewing out as the former Space Marine grew larger and monstrous. Phosis T'Kar's changing form at the Burning of Prospero grew to such proportions he dwarfed Constantin Valdor.[3][38x] In addition to the riot of change that wreaked havoc with their flesh when the condtion took over, in the overwhelming majority of cases when a legionary was lost to the Flesh Change, he devolved into a mindless monstrosity; an especially horrific fate for the Thousand Sons, who took pride in their learning and culture. When the Flesh Change struck the ranks of the Thousand Sons during the final stages of the Burning of Prospero, legionaries who succumbed to the Flesh Change attacked anything within reach, regardless of whether they were Space Wolves or Thousand Sons.[3][38x]

When Ahriman cast his infamous Rubric, the Thousand Sons were cured of the Flesh-change at a stroke, albeit with a heavy price paid - those Legionaries with little to no psychic ability were reduced to dust and sealed within their power armor, little more than automata, while those Thousand Sons with greater psychic ability had their power greatly amplified. It was noted by one of Ahriman's cabal, however, that while the Rubric cured the Legion of the Flesh Change, it did not grant immunity to mutation, as Thousand Sons (such as Ichneumon) who had pledged themselves to Tzeentch, often looked on the mutations granted by their patron god as a 'blessing'.[Needs Citation]


For the Thousand Sons, knowledge is power, and the most knowledgable the most powerful. Arising from the origins of their first recruits and being driven by the early legion's need to discover a cure for the flesh-change and gain deeper understanding and control of their psychic abilities, these linked beliefs resulted in two major cultural factors developing in the Thousand Sons; veneration of the text and veneration of their Primarch.[1]

As a result, the Thousand Sons, while sworn to the Emperor and the Imperium in word and duty, found that at the moment of testing, their loyalty to their primarch and their desire to preserve their acquired knowledge was enough to lead them down the path of damnation.[3]

The Pursuit of Knowledge

The legion's desire to learn how to control their powers developed into a hunger for any and all knowledge. Driven from an origin of self-interest, their desire to know as much as possible and master every discipline available to learn caused them to seek shortcuts or explore morally perilous paths, especially once Magnus and his own insatiable hunger for knowledge encouraged them to progress from simple scholarship into the practice of sorcerous techniques. As a result, they have long held every record of information as a valuable item in itself, as well as a resources to be drained. Ahriman in particular has, since the Heresy, dedicated himself to this desire seemingly above loyalty to his primarch and even to Chaos itself.[1]

While the Thousand Sons have an interest in all forms of knowledge, they particularly pursue items or places that may hold sorcerous power or reference arcane secrets. As a result, it is not unusual at all for a Thousand Sons warband to raid a museum, library or private art collection rather than a military target. And while many Legions sponsor Chaos-worshipping cults, the Thousand Sons tend to use theirs not to overthrow or destabilise Imperial power, but more rather as collectors of items and people they are interested in; much to the chagrin of cult leaders, as when a Thousand Sons warband finally answers a summons, they tend to simply leave with the cult's artefacts and best sorcerous practitioners not long after.[7]


The Thousand Sons battle Necrons

Like all of the Legiones Astartes the Thousand Sons were initially made up of Terran marines. In the aftermath of Magnus' deal with Tzeentch to save their lives, only around a thousand of them were left. For the rest of the Crusade, the Thousand Sons recruited from Prospero, a planet of only limited population (although many of them were psychically active). As a result the Thousand Sons were never a large legion.[3m]

Currently, most of the Thousand Sons Sorcerers arise from the ranks of the Aspiring Sorcerers. These low mages are taken from the ranks of Tzeentchian cult psykers from different planets. They are taken to Tizca, where they conduct the complicated and most dangerous rituals to test their body and mind. Most are torn apart by the sudden influx of empyric energy or are driven mad; others die when their body begins to change, under the influence of ancient technologies and Warp influences. Those few who survive are born anew and become newly made Chaos Space Marines - Aspiring Sorcerers of the Thousand Sons.[40d]

How the Thousand Sons currently maintain their numbers is unknown, although they have been observed carrying out an apparent resurrection ritual at least once. On this occasion the spirits of deceased Thousand Sons were summoned from the warp into mortal bodies (whether living or dead making no particular difference), bodies which then transformed themselves into reborn Thousand Sons.[10b]

At least one Imperial commentator on the subject believes that the Thousand Sons have a cult network that provides potential recruits for the legion.[9b]

Noted Elements of the Thousand Sons

Thousand Sons Armoury

Main article: Thousand Sons Armoury



Known Vehicles


Notable Members

Heresy Era

Unique Troops

Additional Information

Related Articles

Trivia and Notes

Thousand Sons, as depicted in Realms of Chaos
  • The Achaemenid Empire, the legion's first recruiting ground on Terra, is a reference to the historical Achaemenid Empire, i.e. the Persian Empire at the time of Classical Greece.
  • The Thousand Sons being used to pacify Boeotia (itself a reference to the region of the same name in ancient Greece) during the Unification of Terra is a reference to the Greco-Persian wars.
  • Ahriman and Ohrmuzd are the names of the evil and good deities, respectively, of Zoroastrianism.
  • Prospero is the name of the exiled noble, scholar and sorcerer forced to cast aside his works and turn his back on magic in Shakespeare's The Tempest.
  • In Egyptian mythology a pesedjetMagnus' term for the structure of his legion – was a grouping of nine deities.
  • In older source material – pre-dating the addition of the Rubric of Ahriman to the background – not all Thousand Sons were said to be psykers, though all had sorcerous knowledge and various minor levels of magic ability. They operated in effectively the same way – individuals of great power supported by line troops – but for completely different reasons. In addition, earlier edition models and artwork made much use of the trope of Tzeentch gifting physical mutations upon his followers. This trope vanished from the background with the introductions of the Thousand Sons' distinctive visual design, their own unique miniatures and the concept of Rubric Marines, but has since been reincorporated into the background as the Flesh-change.