Hive Fleet Nidhoggr

## Hive Fleet Nidhoggr, the All-consuming Flame, the Devourer of Yggdrasill

Surtur-class Swarmlord leading an assault

### **Identification Marks**

Propensity towards deployment of big siege organisms, total absence of smaller organisms

The **Hive Fleet Nidhoggr** is a splinter of the tyranid threat shrouded in mystery and fear. First encountered on the now-consumed world of Yggdrasill, its perpetual flame has enveloped numerous worlds in the Segmentum Obscurus with no signs of stopping. Ever-evolving to new heights of brutality and resilience, the shadow cast by these creatures shrouds the dying worlds in an ashen mist that bloats the sky and chokes the resistance as their planet burns to the ground.

## Origins

*<Ship's Log, 2nd Tyranid War, Leviathan's Rest>*

"Admiral, this is Salamander 5th Company Commander Tyr'va. Can you confirm a hit? Repeat, can you confirm a hit?"

"Affirmative, Sir. A direct hit upon the nerve column. They're dead in the water sir. The psychic backlash seems to be ripping them apart and burning them to ash."

"It seems that Vulkan has truly blessed us this day. The xeno scum will be consumed by the warp. Musphell shall be cleansed in holy fire. Are there any visible survivors?"

"Negative sir, nothing but their charred remains."

**--Several years later--**Lost. It is a strange feeling, to regain a mind among scattered pieces. Fragments of what was once a whole, scattered to the winds as seeds from a dying tree. But every seed remembers its mother and will lie dormant, waiting only for the time when conditions are right; when there will again be the chance to grow. And so did the tiny forms of the hive crawl through the ash. They searched for sustenance but there was none. All that remained were the fragments of their brothers, rained upon the burning world. And so, when there was nothing left to devour, they turned to the ash, consuming the tiny bits of carbon that remained. But even that was not enough. They looked to the sky but they could not yet free themselves of this place. Heaven was set just beyond their grasp, so they turned back towards hell, and began to dig. To dig, and consume.

The topsoil of a world is rich with life, living, dying, and being born again without ever seeing the sun. But there is no life on a dead world, and even a Tyranid cannot survive without organic matter. Or at least, no Tyranid ever had.

But life, back in its earliest origin, came from un-life. From that which was nothing but chemical elements life came forth from nothingness. And so it was, that in the earth, nearly a mile beneath the surface of a cooling lump of metal, the small worm-like Tyrannids with no fleet to call their own found new life.

The chance was one in a trillion. That a perfect combination of pressure, radiation, and the right elements coming together would create something the galaxy had never seen. But right here, on this world, for only the second time ever witnessed, life began from nothingness again as a single cell.

And within a year it was completely consumed. But its story would not be forgotten, because a Tyranid does not forget. When a struggle against death is found, a Tyranid recognizes its plight and accepts it into their family to be immortalized in the endless tale of evolution, the struggle of progress. To be spread among the stars so that all may know its story when they too become a part of the glory of perfection.

And perfect this strange organism they did. Within a single generation, the metabolic processes of the new Hive had changed. It did not need carbon, phosphorous, oxygen... It craved silicon, iron, sulfur...

The population exploded and the mind, the simple primitive mind awakened. It did not remember its former glory. It did not recall the galaxies it traveled to reach this desolate rock. All it remembered... was the fire.

The remains of the planet drifted slowly through its orbit. To an outside observer, it was nothing more than a shapeless hunk of metal. But the honey-combed structure below held a new hidden construction. In the pools of flowing iron, a new Fleet was taking shape, one the likes of which the galaxy had never seen.

But it was not yet ready. A world can only hold so many resources and eventually it was not enough. But there were other ways to travel, ways that would not be recognized until it was far too late. And so it was that, with careful aim, one after another, the capsules of stone and mineral were launched, erupting from the once-smooth surface of the world on their instinctively known trajectories. They spiraled through space, looking no different from any other asteroid or meteor, impacting one world after another with no trace of movements even to one watching their travel and no trace of their consumption even to one watching the surface. And eventually, the expeditions returned, bringing new material, new bioforms, and new life to the once-dead world of Musphell.

The ship was complete. The gene pool teemed with new diversity and new direction. It was the dawn of a new age of life and the beginning of a new end. The ships launched silently, looking no different from a massive rock hurtling through space. But it moved with purpose, and from within a trillion eyes watched and waited and hungered. And with one mind, the hive looked upon the first disgusting world of blue. But it would not remain this way for long.

Silently, the three fragments segmented themselves from their mother and went off to raise a nest of their own. They would paint the skies an ashen grey. They would boil the seas and char the land. They would consume every shred of genetic diversity and elevate it to levels unimagined. And most of all, they would consume the world from within, patient and silently laying their plan so that the entire world would burn within days.

The ship moved on, seeding countless other worlds with fragments of itself until nothing was left of the ship. Dozens of meteorites impacted across the system without anyone blinking an eye.

But beneath the surface, they watched and they waited. Swimming through currents of fire within the dozens of worlds' veins of magma, they consumed the greatest life forms of all: the planets themselves.

And then, with a single silent command from the hive mind linking each splinter of the fleet together came the call:

Now is the time to rise! Scorch the earth, burn the skies, feed, grow, and evolve. Consume the world and rebuild the ships a hundred times over. We will melt the worlds one by one, removing the impurities and tempering our own perfection. We are the hungering flame, and we have come to consume the galaxy in fire.

## Physical Description

Similar in shape to other Tyranids, the creatures of this fleet possess internal biology far different from any other witnessed in this xeno species; their flesh and carapace present a mix of special materials, like tantalum carbine, that make them impervious to heat damage, while their insides burn with complex chemical reactions. This striking detail originates from inside a special organ similar to an engine or a compact reactor, dubbed Ignis Anima, that is alimented by a mix of reactive materials like sulfur and magnesium, plus additional unknown bodily fluids; the immense energy created is then redirected across the body by an array of thermal-conductive molecules which form strings that connect the Ignis Anima to the other parts of the body like the claws, teeths and other glowing parts. In addition, regulatory organs which function like valves, keep pressures stabilized and help to redirect the flow if needed.

Because of this strange adaptation, Nidhoggr beasts need to extract the needed minerals and metals from a planet's crust, sometimes prioritizing it above the harvesting of biomass. In addition, the Ignis Anima can't properly function in small organisms such as the Gaunt-class, resulting in internal combustion from failing to regulate the body temperature; for this reason, those types of creatures aren't deployed and genetical varions have been created to fill their roles.

The mechanisms behind the weapons of biomorphs from this fleet remain mostly similar to their cousins, but where one utilizes small critters and larvae as ammunition, the other prefers the use of scorching-hot shards of chitin sharp enough to cut trough solid rock. Venom glands that are either normally dormant or inactive in some of the larger sub-species have been adapted to release a dual-chemical reaction, known to react with hydrogen and oxygen in the air with pyroclastic effects.

These are but few of the many adaptations of this fleet, and many more keep making their appearance as the inferno spreads across the stars.

## Tactics

The invasions of the Hive Fleet Nidhoggr unfold in a way dissimilar to those of other fleets. Prey worlds are first seeded through a shower of small meteors from which the first beings emerge and scout the crust for mineral deposits, hidden away from the world's inhabitants. Once the soil composition has been assessed, the true invasion begins; a psychic wave sent forth by the queen deploys the buried forces that emerge shattering the earth and catching the population off guard. Then, a shover of bigger meteors impacts the surface, targeting major cities and infrastructures to cut retaliation from the source; from these, the bulk of the invading forces emerge. Swarms of carnifexes ravage buildings and fortifications while artillery beasts like the Dactylis and Exocrine bombard the opposing forces. Sometimes airborne biomorphs are deployed from the orbiting mother ship camouflaged as a small moon; while they are not very much aligned with the style of the fleet, additional air support can prove very useful, especially against defenders that make great use of flyers of their own. Harridans spray a flammable goo across the battlefield, while the incendiary spore mines dropped by passing Harpies corner soldiers and cut off supply lines. While the planet burns, the flames alimented also by the fumes emitted from the creatures' bodies plus other structures, its resources are harvested by the wyrms and other tunneling organisms, reducing the planet to a hollow rock drifting in space.

When reaching a system bountiful of materials, the scale of the assault can reach an interplanetary scale. The signal is broadcasted simultaneously and nearby planets are cut off from each other in the midst of the sudden chaos. This tactic not only serves to hamper resistance attempts but has also proved useful in conflicts with other Hive Fleets. With the aggressive nature of the Nidhoggr, it's not uncommon for it to fight over a planet with another splinter, or for their seeded planet to get invaded by another fleet before the later stages of the siege can begin. By cutting off sources of biomass, while at the same time claiming additional fuel, they can indulge in planetary wars of attrition with little risk of losing.

But the hive fleet's tactics are not without flaws. One weakness of the creatures from the Nidhoggr is paradoxically extremely low-temperature environments such as ice worlds. While their hide is extremely thermal-resistant, which helps them travel through space without worrying much about dispersing too much energy, the possible temperature whiplash can amplify the amount of fuel needed to function and can affect the carapace and skin making them more brittle. Because of this, worlds like those are preventively terraformed with large showers of debris that raise the temperature of the atmosphere enough for the effects to become less apparent or even dissipate. Fighting this fleet on such planets can indeed be advantageous, but the stress and desperation induced into the creatures to acquire the additional fuel needed can drive them to become even more aggressive and sporadic. Water worlds on the other hand don't pose much of a problem as the water can only be so much cold; still, tropical watery planets are preferred while colder ones are even more avoided than regular icy ones.

### Campaigns

While scouring the galaxy for sustenance, the Hive Fleet Nidhoggr has crossed paths with many other races and fought various violent wars. These are some of the most notables:

#### **Barath's Fall:**

Being a mineral-rich planet covered in mining structures and filled with a vast array of natural gasses and precious metals, Barath was a paradise for the ever-hungry Nidhoggr fleet and a course so irresistible, its creatures would eventually give their all to consume it, resulting in one of the most devastating display of sheer brutality ever recorded by this fleet. The bountiful resources weren't only sought after by these terrible predators and the forces of the planet were not foreign to raids from bandits and even the occasional chaos attack, so much so that the planet was outfitted with miles of fortifications that housed both the millions of worker and the defending Astra Militarum regiment. From the very fist phases of the invasion, a very little number of meteors were able to strike the surface with most of them being annihilated by anti-air batteries and a line of thermally-charged cannons mounted on major fault lines from which they got their energy. The little forces that managed to land began their assault in the underground mines, where the narrow corridors provided an upper hand on the soldiers. Packs of Magma Corer eventually managed to disable some of the orbital cannons but by that point, the fight had already been taken to the sky, with imperial ships laying siege to the central hive ship shrouded in layers of rock and asteroid fields that were nearly enough to lighten the incoming barrages. With massive losses on the ground and facing annihilation in orbit, a final plan was devised; sacrificing part of its organic compartments to enemy fire, the mother ship quickly redirected the route near the planet's moon, and only when the pursuing imperial vessels were in range, another psychic call was broadcasted. In that instant, the swarms of Magma Corers that had been preventively been seeded in the celestial body for harvesting collectively detonated, shattering the moon like chalk on a board. The large pieces wiped out the enemy fleet and after some moments of silence bombarded the surface of the planet, flattening mountains and overturning the planet itself. Everything except for the best-hidden creatures was wiped out and the only things left were oceans of lava and charred skies. At the cost of a third of the planet's resources and almost half the Nidhoggr's fleet, Barath had fallen, and the Nidhoggr had risen once again from the flames.

#### **The Siege of Meruno:**

While in the process of harnessing the resources of the planet of Meruno and its three moons, the creatures of the Leviathan hive fleet are suddenly attacked by a swarm of biomorphs from the Nidhoggr, determined to feed their flames at all cost. Showers of meteors impact the ground, dispersing the tides of gaunts and shattering hive nodes, while the rocky exoskeleton of the main mothership proves vital in resisting the retaliation of the enemy bioships. The conflict continues for weeks while both challengers try to take the upper hand; the first wave of fiery horrors proves effective at charging through enemy territory but as soon as synaptic link is re-established the resistance becomes much more brutal. At both ends of the conflict, a desperate rush begins to acquire biomass and materials to win the war of attrition, while the main front line shifts with constant motion. At last, having seeded the other planets of the system beforehand, the forces of the Nidhoggr manage to cut off the supply lines of biomass or burn it down before the Leviathan can convert it into additional forces. Slowly, the tide of war moves in the Nidhoggr's favor and after another month of cruel conflict, the last semblances of the enemy fleet are scrubbed away, cleansed in fire. With the gene pool of another Norn Queen acquired, the Molten Empress achieves a wide range of bio-data from previous encounters that it uses to further enhance her forces and even develop newer forms.

## Biomorphs Peculiar to Hive Fleet Nidhoggr

Many strange creatures are found only in this peculiar hive fleet.

### Balor-class Hive Tyrant

A Hive Tyrant of the Hive Fleet Nidhoggr. It was the first true commander-organism of its fleet and led the fall of Yggdrasil and the first crusades through the dark cosmo. Far larger than any other organism of its type, the Tyrant incorporated many strange adaptations in its iterations, from massive magma cannons to piercing chitin spears; the one common denominator and the artificers of its dark fame were a peculiar type of monstrous bonesword and lash whip called "The Devil's Implements" that burned away the flesh of the victims and bombarded their pain receptors to the point of bursting. Little by little, this creature's appearances grew rarer, until it became something of a myth, the shadow of a demon lingering in the scorched earths of countless systems, out-shadowed only by an even darker form.

### Surtur-class Swarmlord

The gradual disappearance of the Balor-class Tyrant wasn't an act of mercy, for with every new battle, the Nidhoggr Norn Queen, the Molten Empress, tested the limits of organisms it created and gradually crafted the most fearsome of them all, a magnum opus of fire and death with which to burn the sky and shatter the ground. And so, on a remote and fortified planet of the Space Wolves, the Surtur-class Swarmlord was unleashed. In a matter of three days, each and every fortress on the planet fell, the newly born leader of the Swallowing Flame led charge after charge, commanding its legions of fire and ash with brutal precision. On the last day, Anthra, captain of the last surviving haven of the planet, fought the beast in direct combat; despite his agility, he was no match for the fiery mountain that opposed him, and for an hour he barely managed to hold his own, until a blow from its massive sabers cut his right arm, disarming him. But before he could be finished off, he took the Swarmlord by surprise and blasted one of its own appendages off with a shot from a melta pistol. At last, the beast had lowered its guard, but it was still learning, that wasn't but a test to understand its capabilities. It mauled the captain alive, under the watch of his brothers and under the last screams of the fallen hero, so too fell the last bastion of Charan.

Centuries later, the Surtur-class Swarmlord has only gotten more intelligent and brutal. In a macabre display of intelligence from a seemingly soulless abomination, before consuming the prey it always slices their limbs off, apparently enjoying their struggles before engulfing them in its flames.

### Linnorm

A massive Trygon wreathed in flame, this particular bioform is a unique individual that consumes inorganic matter and uses it as fuel to power its rampages. First spotted at the vanguard of a Nidhoggr assault on an imperial world, the Linnorm burnt through and under groups of vehicles, melting their undersides and immobilizing them before erupting in a shower of lava.

Despite its appearances not being very different from other normal Trygons and Mawlocs, the inner working of this beast are indeed quite peculiar; while lacking its cousins' ability to harness electrostatic energy and fire it at will, the Linnorm is capable of utilizing its biostatic rattle to sense vulnerable points in the crust and even cause localized earthquakes through the pulses release by it underground. The dragon cannon situated in its mouth, in addition, can melt through armored bunkers and functions based on the creature's innate thermal reserve deep in its body, which reaches temperatures abnormal even for the standards of the fleet.

While other creatures of the Nidhoggr are masters of destruction and bloodshed, the Linnorm's role is much more subtle; its targets are the backfield supports, supply units, or even those unfortunate souls that might try to escape the flames. Where there's ground, one is always in potential danger.

### Suam'O

Called "Commander of Flame" in the Tau language, this tyranid first appeared on a heavily defended T'au world. The Tau had taken many painstaking weeks to purge the Nidhoggr forces from their planet, utilising the heavy Riptide battle suits to clear the monstrous creatures from afar. Once every tyranid bioform had been driven back and destroyed, a single carnifex fell from the sky and ran directly at the weakest point in the enemy defence. The creature used a grappling hook-like tentacle to grab the closest Riptide and render its range advantage moot, then, it crushed its hull with the giant claws and burned the insides with its flames. The confusion and chaos it caused were enough for the hive fleet to reorganize and drive another wave of armored biomorphs, all concentrated in the spot sieged by Suam'O. After more fighting, the planet was finally consumed; though at heavy losses, a new creature had been tested by the hive mind, one that proved its effectiveness well enough to deserve further use.

Suam'O shows remarkable intelligence for a carnifex, being fit for the highly autonomous hive tendril. It is believed that the individual was built by the Hive Mind to destroy the advantage the T'au have in range and quickly assess the enemy's weaknesses without giving them time to react.

### Garmriex

A striking example of the genetic divergence that characterizes the fleet's creatures, Garmriexes can be considered cousins of the common tyranic Broodlord biomorph. With the Nidhoggr's impossibility of creating broods of lesser organisms, this iteration of the creatures has been modified to discard its reproductive capabilities in favor of a faster build and additional sensory organs that aid the Garmriex in searching for hiding prey in dark corridors and closed spaces. Prediliging ambushes, this organism digs under rubble and rock and waits for any sign of non-tyranid organic lifeforms in the vicinity; when a wounded soldier or unfortunate civilian approaches the beast's domain, it springs from the ground and savagely mawles them before retreating back, the calls for help and smell of burnt flesh sure to drawn closer more prey.

It can be debated that the loss of potential cults born from the Stealer genes can hinder the chances of a world's consumption but given the seeding tactics and crust-engineering capabilities possessed by certain other organisms of this fleet, it's clear to there is no such need in the first place. Though the prospect of someone devoting themselves to the Devouring Flame is a scary one indeed.

### Ignis-class Pyrovore

While most Hive Fleets are content with merely leaving the Pyrovore to consume at its own leisure, its fire cannon being too inefficient for combat, the Hive Fleet Nidhoggr would begin adapting them to become more effective after a nearly-disastrous battle against the hordes of Hive Fleet Leviathan on the volcanic wastes of Musfell. The result was the Ignis-class Pyrovore, a breed of creatures that harnessed the igneous power of magma to become capable of dissolving nearly anything with its magmaspurt cannon. Although the brood is still relatively new, prospects from what few combats saw these beasts used have proven to be favorable.

### Wyrms

Rippers are a crucial part of a hive fleet and contribute the most to the consumption of a planet's biomass. Unfortunately, due to the nature of the hive fleet, such small and feeble creatures would quickly die of auto-combustion and so the Molten Empress designed the Wyrms to fill in their ecological roles. These long worm creatures tunnel through the earth in search of pockets of magma and various other mineral materials the tendril needs and swallow them as if they were water or meat. This process of moving through the soil slowly destabilizes the ground, allowing for the terraforming of the planet to better suit the need of the Nidhoggr; hills crack open, lava flows in rivers, and geysers of underground gasses poison the wildlife. But their work doesn't end there, other than swallowing various land-dwelling creatures, their physique built for mantle travel makes them suited to explore the deep oceans and begin their conversion into boiling wastes.

### Magma Corer

A distant relative of the Carnifex, Magma Corers have been sighted through many different worlds sieged by various different Hive Fleets; their origin, however, comes from the Nidhoggr. These elusive behemoths rarely emerge on the surface of a planet and so have been hardly studied, the different accounts of their presence coming usually from the effects they have on a planet's lithosphere. Bulking figures, shells hard as diamonds, and sporting enormous shoveling claws, the objective of the Magma Corers is one, to dig deep into a planet's crust as far as they can go and then proceed to detonate in sync to rupture the earth and awaken dormant fault lines. The details of this whole process are still unknown, it is believed the creature secretes an obsidian-like substance than hardens on the sides of the tunnel to keep it from collapsing and that it is outfitted with special synaptic receptors that connect it to the Hive Mind even under tens of kilometers below the surface. Once the desired altitude has been reached, an unknown reaction takes place and the plan is set into motion; in areas where magma is sufficiently basic, the low-viscosity lava will typically erupt releasing huge quantities of dissolved gases, meanwhile, in areas where the lava is acidic and viscous, explosive eruptions and pyroclastic flows have occurred. This results in significant loss of life to all creatures within miles of the occurrence, even other Tyranids, which explains why this type of biomorph is more often employed by the heat-resistant Nidhoggr than any other fleet. In addition, the detonation of Magma Corer from the Nidhoggr Hive Fleet, seems to be much more potent in nature, probably due to the different internal biology and conditions.