Onyx the Indestructible

Onyx
Title/Honours	Onyx the Indestructible, Mountain of Fenris, The Titan-Slayer, Rock of the Empire
Discovered (world)	Terra
Discovered (period)	c.908.M30
Legion	Eighteenth
Great Crusade Command	44th Expedition Fleet
Heraldry/Sigil
Unique Weapon	Two custom artificer power-fists
Distinguishing Traits	Fearless, gregarious, determined
Flaws	Stubborn, blunt, proud
Fate	Lost in the destruction of Neolithus

This page details people, events, and organisations from the /tg/ Heresy, a fan re-working of the Warhammer 40,000 Universe. See the /tg/ Heresy Timeline and Galaxy pages for more information on the Alternate Universe.

"Many powerful people disliked Onyx because he made a habit of telling them the truth, even when it was impolite or outright rude. It was one of my favourite things about him."

(Excerpt from Gaspard Lumey's private correspondence.)

Onyx the Indestructible was the Primarch of the Eighteenth Legion, the Stone Men. The largest and the strongest of the Primarchs, he was a loyal friend and a fearsome enemy. Onyx fought for the Loyalist cause during the Hektor Heresy and continued to fight in the defence of the Reformed Imperium until his mysterious disappearance.

History

Many of the episodes in the life of Onyx the Indestructible seem outlandish, even unbelievable, but to the extent that they can be verified the tales have stood the test of historical science. Some theorise that the Primarch's transcendent nature picked away at the seams of reality, allowing strangeness to bleed into the places he went. Others opine that Onyx was greatly feared by the Ruinous Powers and the most bizarre episodes in his life represent the Hand of Chaos. Our task here is merely to lay out the most reliable narrative.

Youth

According to the traditions of the Stone Men, Onyx the Indestructible was the last of the Primarchs created by the Emperor of Mankind. In this account, the other Primarchs were mere trial runs before the finished product could be assembled, and for this reason the Stone Men and their successors generally hold that the Hektor Heresy was inevitable once Onyx's incubator was stolen away from the Emperor's laboratory beneath the Himalayza Mountains and the Primarchs were deprived of their intended leader.

The Primarchs' loss was Neolithus' gain. A Feral World at the time that Onyx's capsule crashed to its surface, Neolithus was a world of vast, steaming jungles inhabited primarily by a breed of gigantic ant-like cyborgs under the direction of a malevolent supercomputer. We do not know what these creatures called themselves and in Onyx's own account they are referred to simply as "Cybants". Regardless of their identity, the Cybant hive had driven the native humans into savagery and to the brink of extinction, but the coming of Onyx would change all of that. Both the cybants and human hunters nearby saw the descent of the Primarch's capsule and hastened to claim whatever bounty had fallen from the heavens.

Unlike those of his brothers who were welcomed into their worlds by human hands, Onyx fell into the grip of the Cybants. The cybernetic horrors claimed his incubator and carried it away to their lair, where it was investigated by more sophisticated models under the direct control of the central intelligence. After a lengthy investigation, the Cybant hive managed to open the incubator - and infant Onyx, already the height of a human youth, leapt out to smash its sophisticated servitors. The dispatch of warrior models failed to contain the young Primarch and Onyx rampaged through the hive, laying waste to the Cybants until he found the supercomputer itself. The machine tried to bargain with Onyx, but either the infant did not understand or did not care to bargain. With one blow of his mighty fist, the Primarch destroyed a menace that had almost annihilated Neolithus' people.

Destroying the nerve center of the Cybants killed most of the drones. The remainder moved about at random, heedless of any danger until they died. For the humans of Neolithus, it was obvious that a great miracle had delivered them and the wisest among them knew the light in the sky was the cause. Eventually a few bold scouts ventured into the Cybant lair to pick the bones of their nemesis, and there they discovered Onyx supping on Cybant haunch. Incredulous at first, the scouts soon learned that the "boy" was far more than he seemed and hailed him as their saviour. Over the next three years, the Primarch grew to his full stature, mastered the tongue of the natives, was given the name Onyx Lithus - he who banished the night from Lithus - and was recognised as God-King of the Planet. He lived in as much luxury as he desired and directed his adoring subjects to better their condition through many ingenious schemes of his own devising.

This tranquil life was interrupted by the coming of visitors from the stars. A mighty giant in golden armour strode out onto the surface of Neolithus, directing its minions to gather up specimens for his great interstellar zoo. Hybtar the Collector, for the giant was none other than that miserly xenos, was eager to sample the fruits of Neolithus and a creature as singular as Onyx was the most precious of prizes. Although Onyx was too mighty for Hybtar's entourage to subdue, the alien seized the people of Neolithus and threatened to kill them unless Onyx surrendered himself. Above a chorus of weeping, mighty Onyx gave himself up to save his people. From his beloved home, the Primarch was taken to Hybtar's immense space station, there to be exhibited for the amusement of the alien and its guests.

For many days, Onyx raged in his enclosure, trying to smash open an exit even to the killing Void outside. He struggled in vain. For all of the Primarch's might, Hybtar's station was fitted with powerful force fields that secured its enclosures. Only by learning the languages of his fellow captives - the Eldar Princess Yvanna, the sentient crystal Adj'Manax, and the ancient reptilian Bitol q'Thop - through long and patient study could Onyx break free. Bitol q'Thop, nearing death and sensing the character of a true hero in Onyx, gave up the last of its life force to project an illusion through Adj'Manax's crystal structure. This semblance fooled Hybtar's minions into believing that Onyx had escaped and the dupes willingly opened up the Primarch's enclosure to investigate. It was their final act. Onyx quickly freed his companions and then took a moment to honor the long life of Bitol q'Thop before moving on with the next phase of his plan. Princess Yvanna stole away to the station's launch bays, using her people's legendary guile and grace to evade detection. Onyx, with Adj'Manax upon his back, made for the core of the station to seek revenge. While Hybtar's guardians were fierce and heavily armed, but against the Primarch's might they stood little chance. The alien itself was another matter. Adj'Manax had slowly reshaped itself into an armoured carapace around Onyx's vitals and it was this precaution that saved the Primarch's young life when Hybtar greeted its former captives with a blast from an advanced energy weapon. Shocked by Onyx's survival, Hybtar had no time for a second shot before the battle became a hand-to-hand struggle for survival. Hybtar and Onyx fought throughout the station, throwing one another through walls and bulkheads alike until the vast structure's integrity began to fail. Even with the station collapsing around them, the two collusi continued to brawl, until finally Onyx drove them out into the Void. There, the Primarch seized his foe and smote him with a tremendous blow, sending Hybtar hurtling towards the nearest star and annihilation. For minutes Onyx and Adj'Manax tumbled through the Void, slowly growing more distant from the ruins of Hybtar's station. Both were resilient to the rigors of hard vacuum, but it is no exaggeration to say that their lives were saved by the arrival of their comrade Princess Yvanna in a hijacked shuttle.

Adj'Manax's homeworld was long gone, and Onyx had little knowledge of stellar navigation at this point. Only Princess Yvanna knew her way home, and on the long voyage to Sgathan-Ra the three had many adventures, sealing their friendship and discovering strange technologies such as Onyx's Igneous Cannon. Yet their journey did not end at the home of Princess Yvanna. Her father, King Ku'Kyullain the Dark was grateful enough to Adj'Manax and Onyx, but he could not permit the two to stay on Sgathan-Ra. As a token of his thanks, the Eldar King summoned Harlequins to guide his daughter's companions to their rightful home. Before their parting, Princess Yvanna pressed her elegant hands against Onyx's and pledged that they would meet again one day - a scandolous gesture only barely tolerated in the ranks of the Eldar. Onyx's journey through the Webway was bizarre, though the Harlequins' knowledge of the secret ways kept danger at arm's length. In a matter of days, the Primarch had traversed vast reaches of space and arrived at Ancient Terra, the homeworld of his mighty father and the Imperium of Mankind.

The Great Crusade

Colours of Onyx's Eighteenth Legion, the Stone Men.

A lesser ruler than the Emperor might have been startled by the sudden appearance of a towering, heavily-armed warrior in the heart his realm. Not so for the Master of Mankind. When Onyx stepped from the Webway onto the soil of Terra in late 908.M30, he was greeted by a squad of the Emperor's bodyguard, the famous Adeptus Custodes, who praised the Primarch and offered to take him to his father. Tempering his justified suspicion of golden-armoured giants, Onyx agreed to their escort on the condition that he retain his weapons. In the Emperor's throne room, the meddling separation of Chaos was finally ended, though surviving accounts all agree that there was great friction in the meeting. The Emperor is said to regarded His wayward son coolly and asked why he had taken so long to return to his birthplace. This opening prompted an exchange of tales. Onyx began by recounting the story of his birth from the sky and how he had fought monsters on the first day his lungs drew breath, then impetuously asked what the Emperor had been doing at the time. This began a long exchange of tales and boasts, in which Onyx pitted the saga of his journeys from Neolithus to Sgathan-Ra and through the Webway to Terra against the Emperor's record in Great Crusade. At the end of the telling, Onyx angrily insisted that he was born of the sky and not a man, to which the Emperor wryly observed that nobody present was born of a man. Hours of bragging and insulting one another blew over and the two clasped hands in friendship, then Onyx knelt to offer his services to the Great Crusade of Mankind.

These services were much needed. The Eighteenth Legion had been enhanced with Onyx's genetic material but their gene-seed had decayed over the decades. Fresh samples of the Primarch's genetic code invigorated the Eighteenth's gene-seed and allowed the Legion to expand its ranks rather than merely keep pace with losses. While the genewrights laboured, Onyx prepared to test his Legion's true worth. Observing the success of other Primarchs in relocating to the planets on which they had matured, Onyx conferred with Imperial scholars regarding the likely location for Neolithus then mustered his 44th Expedition Fleet to reclaim his homeworld. After much exploring, Onyx finally tracked down Neolithus and was surprised to discover that the world had been conquered by a War Scribes Expedition Fleet several years prior and was now in a state of revolt. The Neolithans had stayed true to the teachings of Onyx and resisted the rule of any other monarch. A six-regiment garrison of Fischetti Numeri was confined to what was rather grandiosely dubbed the planetary capital - in truth, little more than a fortified spaceport. Onyx drew on his authority as a member of the War Council and commanded the Imperial garrison to depart, for which the Numeri were duly grateful.

PROVE YOUR STRENGTH In his last days on Terra, Onyx had a rare opportunity to meet with a handful of his brothers, among them Roman Albrecht, Brennus, and Tollund Ötztal. Hektor Cincinnatus suggested that the towering Onyx might be the strongest of the Primarchs, but what was a "might be"? He suggested that Onyx show his strength in a few rounds of barehanded sparring. Onyx eagerly accepted and squared off with Roman Albrecht. The Lord-Knight put up a better fight than might have been expected given the difference in size, but without a sword in his hand he was no match for Onyx. Brennus fought the second round, showing his fury and power but faring no better than Roman. While Tollund Ötztal looked on, Hektor himself gave Onyx a stern test before admitting Onyx the better. Roman and Brennus moved to congratulate Onyx, but Hektor urged them to be patient and pushed forward the Primarch of the Mastodontii. Though Onyx was undoubtedly stronger than Tollund Ötztal, he was outdone by dishonourable tactics and put to the ground. Hektor declared Tollund Ötztal the victor without Onyx's word of submission and the bout was over.

Onyx's great stature was instantly recognized by the Neolithans. Within a week of the Primarch's landing, the planet had transformed from a hotbed of revolt to a peaceful, happy world. This tranquility was somewhat disturbed by the revelation that Onyx was no longer their God-King, but the Neolithans could endure the thought that their hero's father was their rightful master, especially when the Emperor was a distant name and Onyx the nearby reality. With his homeworld's loyalty assured, Onyx set up the Eighteenth Legion's base of operations and looked to the local youths for fitting recruits. Along with more commonplace activities such as setting up training areas, Onyx sought out a fitting cave to house his comrade Adj'Manax. The crystalline entity settled on Neolithus and in years to come its offspring would be recruited to the Legion. Just as Adj'Manax had shielded Onyx in their adventures, younger crystalline entities merged with the armour of the Eighteenth to provide the elite of the Legion with unparalleled protection.

Before his tasks at Neolithus were done, Onyx was summoned by the War Council. Orks from the northern reaches of the Galaxy had begun a migration into Imperial territory and the 44th Expedition Fleet was needed to stop them. The Primarch did not complain at being taken from his home once more, though much dear to him was there, and gathered his men for the long journey to the Segmentum Obscurus. By the time Onyx arrived in the war zone, the situation was heading to crisis point. Many Imperial Army garrisons had been overwhelmed and the strategically important world Fenris had been invaded. Knowing that the Orks could not be defeated by subtle strategy, Onyx directed his fleet to Fenris and fought a stand-up engagement with the savage Xenos. Over the course of a six month campaign, the Eighteenth Legion withstood repeated Ork attacks before counter-attacking and destroying the centre of the horde. Onyx personally defeated the Ork leader, WarBoss GrunKaFist. Tales of the Legion's stoic courage spread quickly and before Onyx's mopping-up operations were complete his men had been rechristened The Stone Men - and as their leader, the Primarch was dubbed The Mountain of Fenris.

The defining challenge of Onyx's crusades were the Kolossomachy, a six decade struggle against a terrible race of Void-travelling giants. The Kolossi began their invasion of the Ultima Segmentum in 922.M31, striking at Hive World Colossus. Imperial warhips in system slowed their advance but it was quickly apparent that the Space Marines would be needed to halt this menace. Onyx's 44th Expedition Fleet cut short Compliance operations in a nearby sector, leaving behind Imperial Army cohorts to complete their work, and moved to confront the invaders. The Battle of Colossus was a pyrrhic victory for the Imperials, for although the Stone Men boldly teleported into the huge bodies of the Void-going Kolossi to destroy them, the Xenos bombardment killed over two-thirds of the Hive World's population and badly damaged its infrastructure. Imperial Remembrancers dubbed Onyx Titan-Slayer for his heroics at Colossus but the war had only just begun. Barely ten solar months later, the Kolossi were active again at the Feudal World Basajaun. Here the lack of Imperial fleet assets meant that the Kolossi could invade. Several of the great hulks de-orbited and burrowed into the earth of Basajaun to begin their spawning cycle. Onyx arrived in time to battle young Kolossi as they emerged from the planet's crust. He personally slew fifty of the beasts and his gene-sons accounted for at least as many, but they were forced to withdraw as Basajaun began to break up. The initial engagements convinced the War Council that the Kolossi were a serious threat. Onyx's Stone Men were relieved from other duties so that they could focus on destroying the huge Xenos. Shakya Vardhana, Primarch of the Eyes of the Emperor soon joined Onyx in this battle, using his precognitive abilities to predict the moves of the Kolossi. Although the Eyes of the Emperor were very different in temperament to the Stone Men, their long years battling the Kolossi together forged a close bond between these Legions.

The Hektor Heresy

Diagram showing the warp currents of the Parthorum Stream, its key worlds, and Sol.

When Onyx heard of The Voidwatcher's treacherous attack on Terra, he immediately set aside his other business and took his 44th Expedition Fleet to the Loyalist rendezvous at Diamat. The 44th would have a long journey to Diamat and Onyx considered it likely that the battle for Ostium would be long underway by the time of their arrival. However, he felt that the Voidwatcher would not have been so brazen as to betray the Imperium without some kind of plan and was determined to provide assistance if the Iron Rangers, Scale Bearers and Thunder Kings were unable to breach Ostium's defences. In truth, Onyx was too optimistic. On his arrival at Diamat a wave of psychic anguish washed over the Stone Men psykers and Iron Rangers warships were picked up fleeing the system. Despite the Stone Men setting off at a reckless pace, they were unable to catch the Iron Rangers fleet before the traitors jumped into the Warp.

Onyx gathered his fleet together and returned to the inner system to provide assistance to the Scale Bearers. He was horrified to learn that the pyschic emanations were caused by the death of Tiran Osoros at the hands of the Iron Rangers Primarch Rogerius Merrill and greatly disturbed to find many of Tiran's gene-sons struck mad by the death of their sire. After signalling Terra with the grim news Onyx did what he could to help Rychad Owain regroup the surviving Scale Bearers. These comradely efforts had to be set aside when Onyx had a brief but unmistakable vision of his brother, Shakya Vardhana. The apparition spoke only the word Kuniat, imploring the Stone Men to take action. Such visitations had played an important role in the Kolossomachy and though Onyx did not know why the Stone Men were needed so close to Terra he did not doubt the Vardhana. As the 44th Expedition Fleet moved out of the Diamat system, Astropathic communications from Terra explained that Hektor Cincinnatus was in revolt and leading his Legions towards Sol. The vagaries of Warp travel can make a mockery of precise planning, especially when fleets must move over long distances. Onyx's fleet arrived at Kuniat to find the system in Hektor's hands and Traitor warships massing for their final assault. Never doubting the need for heroism against great odds, the Stone Men carried out a swift hit-and-run raid on Hektor's fleet. While Onyx's capital ships engaged the Traitor line, his escorts slipped in to wreak havoc among the amassed macro-transporters. At the end of the short engagement, the Stone Men withdrew towards Terra knowing that they had struck a major blow against the Traitors at little cost to themselves.

On their arrival in humanity's birth system, the 44th received a mixed reception. Many of the ordinary soldiers of the Imperium were delighted to see them, including Shakya Vardhana and his Eyes of the Emperor. Alexandri of Rosskar, now acting as Warmaster of the Loyal Forces of the Imperium, was more sober. In a short holo-council of war, major differences of strategy emerged. Alexandri openly mocked Onyx's plan for a counter-offensive and the two might have come to blows had they been in the same room. Shakya Vardhana managed to ease the tensions and a compromise plan was agreed, with Alexandri's Silver Cataphracts and the Eyes of the Emperor remaining in the Sol Sector to protect Terra while the Stone Men travelled out to recruit the as-yet undeclared Legions.

While they were hardly friends, Onyx first set out to call Tollund Ötztal to war. On arrival at the Mastodontii Homeworld of Tisenjoch, the Stone Men were hailed and informed that the Eighth Legion was deep in mourning for the blood already spilt among the Space Marine Brotherhood. The warriors of Tisenjoch would make no decision until their rites were finished. This flimsy excuse was dismissed with contempt. Onyx demanded that the Mastodontii set aside their sham neutrality and declare for the Imperium in accordance with their vows of loyalty. After twenty-four hours of silence, the Stone Men realized that they were being played for fools and launched an attack on Tisenjoch to cripple the Traitors before they could finish their preparations for war. While the landings went well, the monstrous face of treason was soon on display. The Mastodontii committed a series of atrocities against their own civilians, starting with human shields and ending in the very depths of depravity. After three months of campaigning, in which Tisenjoch's key facilities were crippled and much of the Eighth Legion's heavy equipment destroyed, the Stone Men withdrew from that accursed world and set a course for the Atalantos Worlds where they hoped to link up with Arelex Orannis and his War Scribes.

They never arrived. Once into the Warp, Onyx's Navigators lost sight of the Astronomican at Terra and had to guess their way through the increasingly turbulent Warp. Most of the fleet attempted to drop back to Realspace and tried to make their way back to Imperial outposts. The great exception was the Legion flagship Mount Everest. With Onyx in command, the mighty super-battleship struggled on despite navigational difficulties and a fluctuating Gellar Field. No two members of the ship's complement agree on how long the voyage took or even what exactly happened, but some points are common to their accounts. That the ship itself resisted the touch of Chaos is beyond doubt, if miraculous. However, daemons still boarded the Mount Everest and the Stone Men fought many battles to save their flagship. At the centre of these battles was Onyx himself. The Primarch's struggle was two-fold: he not only fought against the minions of the Ruinous Powers without, but against the lure of Khorne within. Eventually, the God of Fire and Blood sent his minion Balheizihr the Brazen Bull to claim Onyx's soul or his skull, but Khorne had not reckoned on Onyx's will. Despite his burning flesh and boiling blood, Onyx grappled with Balheizihr until the Mount Everest broke free into Realspace, then crushed the daemon's skull with a mighty headbutt and banished it back to the Warp.

Once they had control of their ship once more, the Mount Everest's complement assessed their situation. They were far from their intended destination near the core of the Galaxy. In fact, they had not traveled all that far from Tisenjoch and had arrived at Rosskar in the Segmentum Pacificus. The Mount Everest's instruments were functioning poorly but still detected a warfleet attacking Rosskar. Unphased by earlier arguments with Alexandri, Onyx ordered his men to move to the rescue of his brother's homeworld. However, a rescue was already underway. Though Rosskar had been brutally attacked by the genewrought soldiers of Pallas Eugenesis, the fleet in orbit belonged to valiant Roman Albrecht and was rendering assistance to the remaining defenders. Onyx and Roman met on the Steel Marshals flagship and, after a friendly embrace and exchange of news, began to plan vengeance on the Traitors. They were quickly joined by the Primarch Gaspard Lumey, who had been mustering his own Loyalist army in the Segmentum Pacificus. In the course of the discussions, Gaspard raised the unpleasant possibility that the Emperor might have been killed in the fighting. Onyx disliked this thought but could not rule it out. Before the Heresy began, Hektor Cincinnatus would have been seen as the heir to the Imperium - but no sane man would follow that Traitor now. Who was the rightful heir? In Onyx's mind, the best choice was the most humble of the Loyalist Primarchs: Roman Albrecht. Reaching his conclusions almost as quickly as Gaspard Lumey posed the question, Onyx turn to Roman and said that he must be Emperor if their father was dead. Gaspard agreed and Roman had no choice but to accept his brothers' decision.

Before the settlement of the Heresy could be concluded, the war must still be won. The three Primarchs agreed to a plan that made best use of their Legions' strengths. Onyx and Roman launched a frontal attack on the Traitor forces guarding the Segmentum Solar while Gaspard's Fifth Legion tried to slip through to Terra. Though the fighting was hard, the Stone Men were slowly reinforced by forces scattered in the failed jump to the Atalantos Worlds and made great progress before the Traitors fled and the journey to Terra was only a procession. Onyx found a sorrowful gathering at the Imperial capital, as victory over Hektor had come at great cost. The Emperor lived - though only barely - and Golgothos was among the countless dead.

Personality

Onyx's persona was as large as his mighty body. He shrank from no confrontation and rarely suffered an insult. But those who thought him foolish or reckless frequently suffered for their presumption as the Primarch was a canny and perceptive man whose preference for honourable combat rarely left him undone by scoundrels. His allies were generally glad of Onyx's courage and willingness to sacrifice for shared causes, though those who preferred a patient approach often resented his directness.

Appearance

Onyx was by far the largest of his brothers, a true giant among giants. He stood like a mountain given life and his powerful laugh sounded like an avalanche. His rugged looks tempted many to carry stony metaphors too far, but for all the trappings of inhumanity Onyx's grey eyes were full of the light and warmth that is the treasure of mankind. Onyx cultivated an impressive beard and was rarely seen out of his armour, even on those rare occasions when he was not on the campaign.

Wargear

Few know the truth of Onyx's magnificent armour, but it is none other than the evolved form of the crystalline entity Adj'Manax. For centuries the two have been nigh inseparable and Adj'Manax can consciously respond to the battlefield situation, shifting its composition to ease Onyx's movement, augment his already legendary strength, or reduce the impact of incoming fire.

Sometimes the circumstances forced him to use ranged weaponry. In these cases, he dusted off his Igneous Cannon, a bizarre weapon discovered during the journey to Sgathan-Ra. A variant energy weapon, its effects are often mistaken for blasts of molten rock. If the range of the Igneous Cannon left something to be desired, its effects could be devastating to metal, flesh, and morale.

A fan's attempt at rules

	PTS	WS	BS	S	T	W	I	A	Ld	Sv
Onyx:	465	6	3	8	8	7	5	5	10	2+/4++

Unit type: Independent Character, Infantry.

Wargear: Cragplate Armor, Gloves, Igneous Canon

Special Rules: ADAMANTIUMEST WILL!!!, Very Bulky, Eternal Warrior, Fear, Fearless, HAH! A FEEBLE EFFORT!, Independent Character, It Will Not Die, Master of the Legion, NO YOU FOOLS, THEY RUN FROM US!

Cragplate Armor: It's armor made of rocks, yo. 2+/4++. Gloves: The twin mastercrafted powerfists crafted by the Stone Man's artificers, Onyx never reffered to them as anything other than "My gloves," though he was enthusiastically grateful to their makers. IStrike with the following profile: S:x2 AP1, Armorbane, Concussive, Paired (+1A), Strikedown.

Igneous Canon: A bizarre weapon, to say the least. Shoots chunks of lava. It may not burn as hot as plasma, but its more solid state of matter means that the heat sticks around longer, overheating flesh and circuit alike. It shoots with the following profile: S:7 AP3 Assault 3, 16 inch range, Blast, Deflagrate, Fleshbane, Haywire.

ADAMANTIUMEST WILL!!!: Upon hearing of the "Adamantium Will" of his brothers, Onyx proclaimed that he had the ADAMANTIUMEST WILL OF ALL!!!. Resisting psykers is about strength of character and simply denying the warp's right to affect you, and no one does denial like Onyx does. 2+ deny the witch, baby.

HAH! A FEEBLE EFFORT!: Onyx has zero fucks to give about the following: Concussive, Strikedown, Fleshbane.

No you fools, THEY run from US!: No Stone Man would run in the sight of their primarch. No Stone Man. Ever. They all get fearless.

ONYX SMASH!!! Onyx has two and only two purposes. First, he wrecks shit. 7 S8 AP1 Armorbane, Concussive, Strikedown hits on the charge are going to kill anything up to and including a Landraider. Due to his high strength and resilience, Onyx is one of the more formidable Primarchs, though his low initiative and attacks are definitely a weakness. His immunity to most status affects and psychic powers helps make up for that to some degree. He also makes all his sons fearless, which is just awesome. Not exactly a tactical genius, but he makes a good battering ram.