Lore Explainer: War Zone Octarius

In The Lore Explainer, we take a deep look at the lore behind our favorite games, movies, and books, and talk about the story behind them and sum up what you need to know and how you can find out more. Today we’re talking about the lore behind War Zone Octarius.

We’ve been on a bit of Tyranids kick recently, covering the Tyrannic Wars and Genestealer Cults and even that one time the Eldar messed up real badA big part of that is due to the 40k lore turning its gaze squarely toward the Tyranids faction and putting them front and center for the new edition. But as we settle in for another six months of Leviathan story, it’s worth taking a look at the most recent Tyranids story in the fluff, and the last new Tyranids story presented. Specifically, we’re talking about War Zone Octarius.

A Brief Introduction to Octarius

Let’s start with Octarius itself. The Octarius System sits in the Ultima Segmentum and represents a massive expanse of the galaxy and an area nearly the size of Ultramar. On Imperial galactic maps, it sits just to the southwest of the Malestrom at the galactic core. Octarius’ most notable feature is the Orks’ Octarian Empire, the largest Ork empire in the galaxy. The empire is ruled by a powerful Ork warlord who carries the title The Overfiend of Octarius. Otherwise, there’s not a lot to say about the area – it’s large and ork-infested, but most of its details haven’t been fleshed out.

Inquisitor Kryptman. Credit: John Blanche

The Enemy of My Enemy is My Friend, Probably

It’s time to remember some guys. Specifically, a guy: Inquisitor Fidus Kryptman. You may remember Kryptman from our Lore Explainer on the Tyrannic Wars. Kryptman is the Inquisitor who gave the Tyranids their name and helped create the Imperium’s strategy for dealing with the extragalactic menace. In his role of “Tyranids Expert” he put in meaningful work fighting against Hive Fleets Behemoth and Kraken, helping to stop the advance of those fleets. It was during this process he came up with the uh, brilliant idea to just exterminate worlds the Tyranids were going to eat, as well as those they’d already started invading. The plan was to deny the aliens precious biomass so when they finally did start fighting they’d be notably weaker.

So Kryptman puts this plan into action – and note that even for the Inquisition, this is pretty dire and monstrous, and will ultimately lead to Kryptman being declared a traitor and a radical. It’s during this sweep of worlds which definitely could still have been defended that the Inquisitor comes up with a whole new brilliant plan: Using this exterminatus process to push the Tyranids toward the Ork empire of Octarius. Kryptman had always been fascinated at how brutal wars between Orks and Tyranids could be and figured hey, why not let them fight for a while? So Kryptman gathers his few remaining allies in the Deathwatch, captures a brood of Genestealers, puts them on a space hulk, and sends them off into the Octarian Empire to create infestations which call out to Hive Fleet Leviathan. This plan works, and soon the fleet has redirected itself to Octarius, becoming locked in combat with Orks who are just completely excited about their new lives of constant warfare against an unending swarm of foes.

The good news is that this leads to a break in fighting for Imperial Worlds along the Octarian Fringe. The bad news is that Imperial observers soon note that the Orks are growing larger and tougher on their diet of constant warfare, while the Tyranids are devouring more biomass and creating new and more diverse bioforms. Rather than weakening, both sides are becoming stronger, like a boxer with a fantastic sparring partner. Many in the Inquisition began to worry that Kryptman had at best delayed the inevitable and at worst doomed them to fight some new, unbeatably monstrous opponent.

Note: The timing on the Octarius campaign is split across the events of the Thirteenth Black Crusade. Kryptman’s plan all starts before the Crusade begins, and in the middle of all of this ongoing war to contain the Ork and Tyranid fighting, Cadia will fall and the Great Rift will open up. This will impact the war itself in one or two minor ways, but it’s more an interesting chronological note.

The Cordon Impenetra

None of this goes over well. Kryptman was already Persona Non-Grata in the Inquisition for his genocidal plans, but it soon became clear that the war Kryptman had started was going to spread. Enter Inquisitor Nashir Sahansun, an older Ordo Xenos Inquisitor who had initially been known as a brawler until wounds sustained against the Hrud left him unable to fight. He’d later become known for his tactical acumen in warfare. Sahansun comes up with the idea to block off the conflict with a spherical perimeter called The Cordon Impenetra. Systems and worlds outside this sphere would be protected and reinforced, and everyone inside the sphere was uh, just left to die, mostly. The planets just on the border received the most support, becoming Warden planets, heavily fortified against Xenos attacks to pursue a policy of aggressive containment.

While this is going on, the Inquisition and allied marine chapters are still heading into the abandoned areas, conducting missions to and strikes to deal with breakouts and to encourage a stalemate between the Orks and Tyranids, sabotaging either as needed. The Deathwatch are major players in this, as are the Celestial Guard, White Panthers, and Silver Templars chapters of Space Marines. These missions are also important for reconnaissance, as the combination of the Shadow in the Warp and the massive amount of Waaagh! energy generated make it generally impossible to send messages through the sector.

Sure, Sahansun had his critics – some believed the Imperium just couldn’t keep up fast enough with the conflict for this to work. Others felt the Imperium should head in and get involved. But Sahansun thought a direct attack would fail, and just when the Cordon Impenetra had reached about half its necessary strength, all hell broke loose.

Credit: Robert “TheChirurgeon” Jones

The Pankallis Breakout

The first instance of the Octarian war breaking out of the Cordon was into the sub-sector of Pankallis. There’s some pretty strong evidence of Chaos shenanigans being behind this, as it comes pretty much out of nowhere and accompanied by mysterious warp storms and other phenomena. Plus, Chaos armies are also in the mix of forces attacking Pankallis in the breakout, and that’s a pretty clear sign.

The biggest problem the Imperium faces at this point is that the attacks are happening over such a wide area – Tyranids attack the Anelanni and Bianzeer’s Hollow Systems, while Orks attack the Kernak system, and both and Chaos forces attack others. Of these, Bianzeer’s Hollow was deemed the most important, as it was closest to Sahansun’s base of operations and acted as a shield for the Octos system.

Note: This is definitely one of those areas where you have to just ignore the insane impossibilities of trying to cordon off 3D space with massive dark gulfs separated by light years – the average distance between stars in the milky way is about 4-5 light years – and just go with it. At least they acknowledge some of this in the recent Leviathan War content, with the Tyranids attacking Imperial worlds orthogonally to the galactic disk.

The Dark Krakens

Octarius introduces us to the Dark Krakens, an Ultima Founding Successor Chapter of the Salamanders. The Dark Krakens hail from Naktis, an ocean world in perpetual darkness whose marine fauna all have bioluminescent properties. As a chapter, they specialize in fighting in the dark, underground, and in nautical engagements. The Dark Krakens were featured in White Dwarf #466 as part of a Flashpoint: Octarius article. There’s some cool fluff about them in Octarius Book 1: Rising Tide about engaging in one of the few instances of Imperial forces protecting local xenofauna.


During this period, the Imperium plays the long game, treating battles in the system like a war of attrition. They allow Ork and Tyranid forces to engage each other, and only intervene when both forces have sustained heavy damage. This mostly worked out, despite heavy interference from Genestealer and Heretical cults. The problem is that, well, space is really big, and there are always other directions to attack from. It was only a matter of time before war broke out elsewhere.

Credit: Robert “TheChirurgeon” Jones

The Veloria Disaster

While pretty much everyone hated Kryptman and his dumb ideas, not everyone was on board with Sahansun’s idea, either. Enter Inquisitor Athocles Van Roth, who was looking for ways to be more proactive, working closely with Deathwatch teams. One of these teams discovered an Ork Mekaniak invention that could disrupt Tyranid Synapse signals and was able to seize it for imperial use. Van Roth himself was not averse to using xenotech for fighting xenos races, and started experimenting with the device – called Baddkrasha’s Crown – to find ways to make it work.

After the requisite justified sacrifices in the name of Imperial progress, Van Roth settles on the Maiden world of Veloria, where Tyranid and Ork forces had already been clashing. They try over and over to use the Crown and nothing they do works. In fact, it likely attracts a bunch of Orks, and they’re forced to try and fight their way out by traveling to an Eldar spire and blowing it up to buy themselves some escape time. They’re joined in this by Aeldari forces, and as you might expect working alongside the Aeldari is not something the Deathwatch are particularly jazzed about. The whole thing ends in disaster, with everyone pretty much getting murdered, the Crown being lost, and a lot of desperate self destructs.

The Role of the Aeldari

The Imperium aren’t the only ones going scorched earth to prevent things from spreading – the Aeldari are similarly invested in seeing the Tyranids defeated and also hate the Orks. In a nice little parallel of “we’re not so different, you and I,” they aid the effort by detonating a bunch of psychic doomsday devices across the sector to stem the Ork tide and slow the Tyranid advance. Asurynai and Corsair forces would end up helping Van Roth and Deathwatch forces on Veloria and ultimately were responsible for detonating


The next big breakout comes to the Sigma-Ulstari system, a location of major import for the Imperium thanks to housing an important Forge World. They initially fight off an Ork invasion, then call for extra help expecting more waves to come. Good call – Tyranids and Orks show up shortly afterward for a second round.

In one of the funnier moments of the story, the planet’s defenders hoot and holler as the Tyranids descend, dropping spores into the planet’s massive oceans of toxic waste, only to shut up when it turns out the Tyranids have just adapted to not be bothered by it. Whomp whomp. Things go pretty poorly until the Black Templars and Helbrecht show up to smash the enemy fleets in orbit and then kill a ton of Orks on the ground. Helbrecht kills Warboss Wurldkilla, basically ending the Ork invasion.

Credit: Robert “TheChirurgeon” Jones


Despite all of this focus on the Imperium and its futile efforts to hold back a massive war between other races, the main conflict was still between Orks and Tyranids in the Octarius System. The war there continued to rage on, eventually reaching Octaria, the captial world of the Ork empire and seat of power for the Overfiend of Octarius. The fighting there is intense, and the Tyranids start consuming biomass on nearby worlds to build up what they need to conquer Octaria, but those ships are lost in the warp when the Great Rift tears its way across the galaxy. That’s when a bunch of Khorne demons attack and further weaken the Tyranid forces.

The Blood Crusades

After the Great Rift opens up, daemons just come spilling out. Particularly Daemons of Khorne – Khorne’s followers were having a literal field day in Octarius, just getting in there and fighting everyone. Alongside World Eaters, the followers of Khorne killed a bunch of Orks and Tyranids in a series of nasty saves called Blood Crusades, then just kind of left to go fight other stuff. Daemonic hordes of Bloodthirsters turn out to be a real problem for the Tyranids, who get no sustenance from killing and eating daemons.


Once the Daemons leave, battle picks back up between the Orks and Tyranids like nothing happened. The Overfiend notices he’s winning the war now that the Tyranids have been hurt by daemons and starts pressing the advantage. The Swarmlord realizes this is a bad deal for the Tyranids and so it needs to make a surgical strike to remove the Overfiend. Unfortunately for the Swarmlord it’s no match for the Overfiend, who crushes its head in a power claw and then rips it in half. The Tyranids make a fighting retreat while the hive fleet spawns a new Swarmlord.

At this point the tide begins to turn back in favor of the Tyranids, who have been consuming smaller Ork worlds and adapting to threats on others. They deal with the Beast Snaggas on Badsquig by creating toxic blood, making it less enticing for the Orks and their mounts to eat their kills. They also start surrounding their bigger monsters with small bugs, making it harder for the snaggas to get good kills, making them frustrated and pissy.

On Octaria, the new Swarmlord takes a more methodical, patient approach, creating a massive blockade around the planet to prevent reinforcements from arriving while biding its time as the ground wars rage on. It’s slow going, but the Tyranids steadily chip away at the Ork defenses. The Orks run low on ammo, their weapons become blunted, and in the fighting the Overfiend suffers a leg injury from a carnifex’s death throes. That’s when the Swarmlord finally steps in and, after a long battle with lots of deft dodges and wild attacks, finally gets an opening and kills the Overfiend, securing victory for the Tyranids.

Following the death of the Overfiend, the Orks decided to get out of Dodge. They start retreating as the Tyranids have turned the tide on the war, possibly irrevocably. Kryptman’s plan has played out, though whether to success or failure, no one is sure.


Credit: Robert “TheChirurgeon” Jones

Notes and Final Thoughts

Thus concludes (for now), the story of War Zone Octarius. It’s a story that started some time ago – the first mention of Hive Fleet Leviathan is in the third Edition of Codex: Tyranids, where it is mentioned that Inquisitor Kryptman has alerted the Adepts of Terra to a new assault coming from “below” the galactic plane. This is also the first mention of the Tyranids attacking the Ork Empire of Octarius, though at that point it was more just something that Imperial observers were smugly noting as a potential upside rather than some plan.

This would change with the 5th edition release of Codex: Tyranids, when Kryptman becomes a “former” Inquisitor after being cast out following his destruction of a dozen worlds to slow down Hive Fleet Leviathan. This is also when his plan is fully detailed – the Deathwatch capture of Genestealers, redirecting the tendril of Leviathan to Octarius, and the concern over the eventual victor being too strong to defeat. This book details the fighting on the Ork world Ghorala, and how Tyranids can not only survive the Octarius War but thrive in it.

Most everything else here comes from the campaign books released in 9th edition – War Zone Octarius, Books 1 and 2 – Rising Tide and Critical Mass, respectively. These books were written with a codex release cycle in mind, and involve the factions released around the same time – primarily Orks and Black Templars, as Tyranids would have to wait for War Zone Nachmund before their book released. The Cordon Impenetra, the Tyranid victory over the Overfiend, and Inquisitor Sahasun are all new additions, and bring the story closer to its present day point than any of the lore written before.

On the whole, the story of Octarius is an interesting idea, but the execution leaves a bit to be desired – the story itself barely focuses on the Orks-vs-Tyranids concept supposedly at its core, and instead spends a ton of time doting on the doomed attempts by the Imperium to contain everything. There are certainly some fun concepts here, but the Ork Empire of Octarius feels under-explored and the Tyranids are, well they’re Tyranids so there’s only so much you can do with them character-wise. It will be interesting to see what, if anything, GW does with this war zone in the future.

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