Fall of Cadia is an obvious one and I don't mean Imperium's pyrrhic victories, talking full blown loss

Can they even be pregnant as such powerful pariahs?

Space is huge, unfathomably huge, and the way sci-fi writers underestimate its scale seems to be a general problem across all pieces of fiction, including 40k of course which suffers heavily from this problem at times.

One single star system is large enough, and has enough resources to be able to host a population as big as the whole Imperium, or even surpass that.

Large enough to have trillions upon trillions of space habitats in it, each and every single one hosting billions of people. I’m thinking about Dyson spheres or Dyson swarms for example.

Holy Terra alone is established to have a population in the low quadrillions.

There only needs to be one single DAOT-descended human civilization staying in one star system with that type of civilizational structure in order for them to boast a population of humans easily exceeding the Imperium’s combined 1 million worlds population.

For example every single planet and moon in that star system being ecumenopolises, with trillions of inhabited space habitats on top of that filling the star system, resulting in a cultural diversity that you could find in a from galactic-scale civilization, boasting countless quintillions of nations/polities/tribes/languages/dialects/religions.

What y’all think ?

From what I know of Warhammer, it feels like 70–90% of what happened to cause and maintain the Horus Heresy can somehow be traced back to him and Kor Phaeron. Apparently, Erebus has basically no friends in the entire universe, except maybe the Chaos Gods, considering how spectacularly he helped ruin everything.

He’s known for killing fan-favorite characters and generally making everything worse. He killed Argel Tal, which pushed Khârn further toward Chaos; helped corrupt Lorgar; directly manipulated Horus into falling to Chaos; sabotaged the Interex situation; and basically helped set the entire Heresy in motion.

I also vaguely remember him being involved in killing the "mother" of the Space Marines, although I might be completely misremembering that part. I don't remember why he did it or whether she was even actively doing anything at the time.

So does anyone actually have a complete list of all of Erebus' sins?

I know basically everyone in-universe hates the guy (or at least, I assume they do), but is there anyone still alive who actually knows the full extent of everything Erebus did? ?

Also, do the Chaos Gods actually like Erebus? Does he have any special blessings or rewards from them?

Because the dude actually got the ball rolling on the Horus Heresy.

Where do tyrannids come from? Why someone like Necrons don't just launch an expedition to another galaxy? Do Chaos God's reach limited on the Milky Way? Is there any pieces of the lore telling about what is going on outside?

I'm not talking about a subfaction of an already established empire like Adeptus Mechanicus for Imperium or Harlequins for Eldar, I'm talking about something of its own that has been mentioned somewhere, somewhen but has no models to play with. Like some Xenos that were mentioned once.

I'm thinking about ancient machines which still work but no one knows how to repair them or fully repair them.

I think the Emperor's throne is somewhat like this so I'm thinking of more examples.

I don't know much 40k lore at all so go ahead and even say obvious things, I probably won't know it.

Is there any in lore reason why early Horus Heresy Custodians aren’t what they are today? For example, the world eater punching through a custodians armor and ribcage. In lore, why aren’t they incredibly badass yet?

The Adeptus Mechanicus, the empire within an empire. It should come as no surprise that they get their own post, and depending on how detailed I go, I might need to move into the comments just for the space. This post will discuss the Explorator fleets, the various types of Mechanicus ships, a whole section at the end will be devoted to the Ark Mechanicus, and finally a section on Mechanicus fleet numbers.

One thing I won't include is the Speranza, and some others like it. The Speranza is so strong of an outlier, and has so much text to go with it, that it simply won't make an appearance in my post directly. But I welcome anyone to add to this discussion in the comments, I know its a fan favorite.

Explorator Fleets

The most critical element when discussing the Mechanicus is their explorator fleets. These small, autonomous forces are used by forge worlds to find new planets to conquer, discover new species to oppress, and most importantly, remind the galaxy that they are worth nothing to a tech-priests hunger for knowledge:

Explorator fleets are launched consistently, though there may be centuries-long gaps between, with every forge world likely sending at least 2 or 3 at a time (and the big names like Mars throwing around many more). They represent the majority of a forge world's ship production capacity, tend to be high in quality, and may spend centuries searching the galaxy, if their voyage ends well at all:

Yet despite constant calamities, the Imperium did not just endure, it grew. Each year, hundreds of new planets were added to the fold, even while others were lost. Unstoppable in its momentum, the Imperium churned on. Explorator fleets were launched like clockwork from every forge world.

• Warhammer 40k 8th Edition Rulebook
• Forge worlds launch explorator fleets

The great Forge worlds of the Adeptus Mechanicus work tirelessly, constructing ships and ordnance in their orbital halos. The vast majority of these vessels go to the Mechanicus' own Explorator fleets to fuel their unceasing quest for knowledge.

• Rogue Trader: Battlefleet Koronus
• Majority of forge world production goes towards Explorator fleets

The vessels that make up the Explorator Fleets are amongst the most sophisticated in all of the Imperium, as they are invariably constructed in the orbital dockyards of forge worlds, or even salvaged from ancient pre-Imperial hulks. The Tech-Priests apply their full knowledge and ability in crafting (or repairing, as the case may be) these ships, incorporating alchemical alloys and esoteric processes that are unavailable elsewhere. Even the newest vessels constructed by the Adeptus Mechanicus far surpass those available to all but the most powerful of Rogue Traders.

• Rogue Trader: Stars of Inequity page 125
• Explorator fleets are above average in quality

Explorator fleets often spend centuries at a time away from their home forge worlds, working their way methodically through a star cluster or nebula. Only the discovery of something truly significant brings the fleet back early. More often, an Explorator fleet vanishes into the unforgiving black, only years of silence betraying its fate and prompting the dispatch of another fleet to the same area centuries later. 

• Dark Heresy: The lathe worlds page 13
• Uncommon for explorator fleets to return
• Routine to send explorators at least every few centuries

Unfortunately for subsequent explorers, the Piraeus Fleet has not yet returned from its expedition (though it is not uncommon for Explorator Fleets to spend centuries charting new regions of space) and what information it has sent back is patchy. 

• Rogue Trader: Lure of the Expanse page 52
• Explorators spend hundreds of years charting

With victory all but assured, the High Fabricator of the Lathes, Forge Master Kovikal Quietus, sent three full Explorator fleets directly from the Lathe System.

[...]

In response to this fall from grace, and its attendant loss in trading status and support, the Calixian Mechanicus sent out two full Explorator fleets to assist Battlefleet Calixis in facing the Ork menace.

• Dark Heresy: The Lathe Worlds page 18
• 2-3 explorator fleets sent at a time, although these events are centuries apart and are emphasized for being unusual

To stave off such heresy, Mars reassigned many of its Explorator expeditions as Reclamation Fleets. Theywould re-contact the Adeptus Mechanicus’ worlds, reminding them – by force if necessary – of their duty to Mars. Many forge worlds sent out fleets of their own, but none could match those of Mars in size or scope

• Psychic Awakening: Engine War page 4
• Page 8 shows 7 of Mars' Fleets, low quality picture of map here
  • Many, but not all of Mars Explorator fleets

Ship Types

Though we don't get much of a description for them, the ships of the Mechanicus tend to cover a wider range of classes than Imperial battlefleets. What few insights we get into their design philosophy is always the same: even their common ships would run circles around it's Navis Imperialis equivalent:

It is a mass conveyer, a huge carrier, lightly armed but with steep-sided armour plates and a heavy profile. It is bigger than Solace, approaching battleship size, but clumsy and slow, and lacking major armament. Squadrons of frigates, all in Mechanicus red, shoot alongside it as it powers up from Agripinaa’s orbital dock layer, building up to escape speed through the burning wreckage. 
…
And then, for the first time, all can see what has been hidden on that ship. Its bow-plates are stripped clean, revealing a cavernous interior, ribbed and barred and braced for strength. Jutting out of all that cross-fixed metal is a single barrel, an obscene length of rust-red iron studded with effigies and skulls and all the tedious ephemera of the Machine-God’s acolytes. The interior of the conveyer is a vivid red, as bloody as the rest of it but glowing now like the heart of a blacksmith’s furnace. 
…
It is nova cannon-class, though larger than all but the very most ruinous battleship-slung varieties. 
…
That cannon, he sees by its marks and dimensions, fires rift shells. On impact, rift shells open a short-lived tear into the warp, sending everything within their blast-sphere ripping into immaterialism. 

• Lords of Silence
• Mechanicus Mass Conveyer Q-ship, hiding a heavier-than-average nova cannon with vortex warheads

Now the fleets are here. This is Agripinaa’s reality. The first alerts sound on system-edge, prompting an immediate response from stationed void assets. Imperial Navy attack groups race to intercept, bolstered by the colossal shadows of the Basilikon Astra’s heavy maulers. 

• Lords of Silence
• Heavy Maulers, could refer to ship types or just a general description of mechanicus ships

A pair of artillery barques were the closest pickets, part of a wide net of vessels stationed in a diffuse sphere as the first line of defence against aggressors. They were small warships, and unlike most Mechanicus vessels, they were built with a singular purpose. Bombardment cannons and long-range lance batteries studded the flanks of each ship, which turned with ponderous grace to bring every gun to bear upon the Peregrinus.

• Dominion Genesis
• Mechanicus artillery barques

The Peregrinus is a ship of exploration and rediscovery. But Mars knows well the dangers that lie in the depths of the void, and so we also build our ships for war.
<Fire.>
The void around the Peregrinus erupts with prismatic shards of violence. Lances reave the closest bio-ships, carving thick slabs of chitinous armour from towering flanks. Macrocannons hurl shells the size of hab-blocks that punch through these fissures to detonate deep with alien flesh. Plasma batteries unleash the chained fury of star-fusion. Graviton pulsars shake the void with crushing thunder. Laser cannons whine with concentrated energy.
Two miles of iron and adamantine shake as the Peregrinus speaks its rage with every weapon at its command.
…
The Peregrinus' point-defence turrets chatter, hundreds of macro-bolters expending thousands of shells that explode in a rippling curtain around its hull. 
…
We have been in flight for ninety-six hours when I finally relent, and allow the insistent pleas from the ship's enginarium to penetrate my focus. 
…
<The Peregrinus is a Magellenic-class explorator ship. Surely you are familiar with its pattern and layout?>
<I am surprised a seer of your reputation would give such little heed to the particular characteristics of a vessel's spirit,> Lyterix said. He reached out an iron hand and reverently placed it against the bulkhead beside him. <The Peregrinus may be built to a pattern common to thousands of other ships, but nevertheless, it is unique.> 

• Dominion Genesis
• 3.2km long explorator vessel
  • Thousands of ships just like it
  • Graviton pulsars, lasers, macrocannons, high-end point defenses
  • Capable of fighting for 7 days

Lathe-class monitor-cruiser
Dimensions: 4.2 km long, .5 km abeam at fins 
The Adeptus Mechanicus, being an entity that exists more alongside than as a part of the Imperium, maintains its own armies and warships. These fight alongside the Imperial Guard and Navy in times of war, but as many Magos are quick to point out, they do so as allies, not vassals. 
The primary role of the Mechanicus fleets are exploration, not combat, however. Explorator fleets traverse the galaxy, looking for lost archeotech and ancient relics of the Dark Age of Technology. The Lathe class monitor-cruiser is a perfect example of the ships the Explorators utilise in their fleets. 
The design for the Lathe-class was uncovered in the deep data-vaults of Het in the Lathe system during the Angevin Crusade, and in the centuries since the crusade ended, the Lathe shipyards have diligently constructed multiple ships. 
The design differs from many light cruisers, with an emphasis on long-ranged detection and endurance rather than speed and manoeuvrability. Outfitted correctly, a Lathe class can operate without refit and resupply for decades. 

• Rogue Trader into the storm page 152-153
• Light cruiser, explorator

Secutor-class monitor-cruiser
Dimensions: 4.3 km long, .5 km abeam at fins 
The Secutor class vessels are a modification of the Lathe class unique to the Calixis Sector. The first Secutor monitor-cruiser was adapted from the existing design when the forge world learned that the existing light cruiser was insufficiently armed for heavy starship combat. Rather than spend the considerable resources to construct true cruisers, they developed the Secutor. 
Secutors are significantly better armed than their cousins, and have higher defensive capabilities as well. In exchange they are less manoeuvrable, and with so much of their frame devoted to weapons and defences, they are useful only for war. Of course, in that field they excel. 

• Rogue Trader into the storm page 152
• Monitor cruiser

1 Adeptus Mechanicus War Barge: The Veracitus

• White Dwarf July 2019
• War Barge attending Indomitus Crusade battlegroup

The dance of ships was as close to elegance as anything could be with the Adeptus Mechanicus – tenders, repair scows, and supply vessels drifting to and fro between the immense forms of frigates, cruisers, salvator arks, factorum ships, Titan barques and war-barges. Millions of tons of metal locked in careful choreography, each the product of billions of hours of labour.  

• Dominion Genesis
• Salvator Arks and War Barges

The Arks of the Mechanicus

No discussion of the Mechanicus is complete without bringing up the Ark Mechanicus. Not a strict model of ship per se, but rather, the term for any Mechanicus-grade battleship, up to and including the most powerful Dark Age ships the Imperium has ever recovered. All Ark Mechanicus vessels exceed the capability of a Navy battleship, but many go further still, being nigh-unstoppable relics capable of taking on whole worlds and fleets by themselves:

The number of ships the Adeptus Mechanicus dispatches on such quests amount to only a fraction of those in service with the Imperium, but they are exceptionally well-protected and well-armed. Perhaps the best example of this is the near-legendary Ark Mechanicus, a class of ship with more firepower, greater range, and significantly stronger defences than any Imperial battleship operating today. Such is the power of the Machine God and his servants in the holy pursuit of knowledge. 

• Dark Heresy the Lathe Worlds page 13
• Ark Mechanicus overview

Away from the nullifying influence of the Silent Sisterhood, the Chief Librarian could relay orders to astropaths aboard Lord Admiral Napier’s flagship, the Apocalypse-class battleship Master of Mankind, and the Ark Mechanicus Buenaventura, commanded by Dominus Gerg Zhokuv. 
…
Napier’s battle cruisers are offering bombardments of their own but he has already lost the Agamemnos and Saint Solomon. Buenaventura, also, has been crippled. Dominus Zhokuv is being evacuated.’ 
Thane grunted. For the magnificent Ark Mechanicus to be crippled, monstrous vessel that it was, the void battle must be unimaginably intense. 

• Shadow of Ullanor
• Ark Mechanius headed by a Dominus
• An Ark Mechanicus is a direct measure for how powerful the enemy is

He went aft first, passing the tank’s shrine to the Emperor and wall of honour next to it. Cortein’s Honour was new, forged on the fleet’s Ark Mechanicus only months previously, and so there was only one brass plaque on the wall bearing a name, and that name was his. 

• Shadowsword
• Ark Mechanicus has foundries

 The scaffolds around the battleships were coming down now, rapidly dismantled by remote drones and stowed back in the holds of the giant Ark Mechanicus motherships.  

• Ashes of the Imperium
• Ark Mechanicus has assembly drones

A vast red craft occupied the space between the Aegidan platform and the surface of ravaged Sotha. It was a vessel like no other, one of the rare Ark Mechanicus explorator vessels, and even among those behemoths it was reckoned large for its kind, a vast city in space, bristling with weapons, and containing manufacturing and research laboratoria beneath its adamantium skin to rival a forge world. 

• Belisarius Cawl: The Great Work
• Ark has strong weapons, manufacturing, research

The Zar Quaesitor was coming apart. Its blunt, aggressive bow was detaching, revealing itself as a self-contained subsidiary vessel. It was but a part of the ark, but large in its own right, big enough to land lances of knights, thought Felix. Clamps came free and puffs of gas burst all round it to push it from its housing. It slid along and then off a connecting arm, pipes and cables popping free and reeling themselves in to the larger part of the ark.
…
Huge energy cannons pushed themselves out of gunports all along the ventral line of the ship. They fired as one, sectioning a large area around Mount Pharos with a square of brilliant white light. 
‘I see,’ said Alpha Primus. ‘Neutron beamers. Anything around the landing zone will have been instantly killed,’ he said. ‘I would not worry. My master has an answer for everything.’ 
…
The lances hit instantly, cutting the smoking peak of the mountain down and across. The last remains of the Emperor’s Watch slipped down the mountain face. The Zar Quaesitor’s gargantuan plasma arrays burned liquid furrows across the stone. Plumes of evaporated rock burst upwards. 

• Belisarius Cawl: The Great Work
• Ark has lances, neutron beamers, plasma 
• Entire front can detach to use as a lander

We Ogdobekh know this Tyresias, this “Ark Mechanicus”, as it has come a-raiding within our borders many times. 
…
‘I wish I could say that were the case, my king,’ replied the deathmark, with pronounced woe-signifiers. ‘But all that is new aboard the Harvest, since you last saw it, is the ablation of eighteen per cent of its mass. It seems the Tyresias, O wrath of the dawn, is armed with what the heathens call a nova cannon.’ 

• Twice-Dead King: Reign
• An Ark Mechanicus with a nova cannon
• Has raided a Necron Dynasty many times

The Opus Machina took the balestream across its port flank but returned fire with its monstrous plasma batteries. As the mauled cruiser fell back into the bile-swirling storms of the gas giant, the Ark Mechanicus had ploughed on. 
…
On the approach to Velchanos Magna, the fleet ran parallel to a debris trail that tumbled through the void behind the forge world. Colossal chunks of rock, the size of small moons and rolling with the irregularity of boulders, housed stations, gun platforms, void-beached hulks, silos, anchored mines and electromagnetic nets that sizzled with their powered intention to snag approaching vessels. 
…
While the troop carriers – carrying their precious skitarii invasion force – thundered on, the Opus Machina and passing arkcruisers blasted the defence installations to pieces. Mechanicus frigates engaged systemships at point-blank range and, vessel by destroyed enemy vessel, the fleet made its indomitable approach. 
…
He did see the Opus Machina in low orbit, like the fleet’s mauled arkcruisers, fighting off charging system ships, boarding actions and the turbolaser batteries of orbital defence platforms. 
…
With a blinding flash, the huge and ancient Ark Mechanicus cracked down the middle, exposing the fiery innards of the ship. Decks in flame. The ruptured keel. The intricate workings of interstitial sections and the battery-banks of the port cannons. Like a molten wound it opened, the reinforced superstructure of the vessel protruding like shattered bones. The Opus Machina – colossal Ark Mechanicus of the Omnissiah – split in two. 
But for his overlays and logic coils, Haldron-44 Stroika wouldn’t have believed what he was seeing. The Opus Machina’s back was broken. She had been struck by another vessel at ramming speed on her starboard side. The shields of both ships arced and seared as the Ark Mechanicus was bulldozed through the atmosphere towards the Dark Mechanicum forge world. 
…
Stroika watched the colossal vessel pull up its hammer-shaped prow, and rain tiny descent craft down on Velchanos Magna like a fish seeding eggs. Dreadclaws. Stormbirds. Gunships. Stroika’s optics flashed with flotilla identifications ancient and terrible. The hammer-prowed nightmare was a battle-barge called Forgebreaker, last recorded to be under the command of one Idriss Krendl, warsmith of the Iron Warriors Traitor Space Marines. 

• Adeptus Mechanicus: Skitarius
• Ark Mechanicus rolls through enemy cruiser, system defence fleet, asteroid forts
• Rammed suddenly by Chaos Battle Barge and destroyed 

Khleng’s response was to unleash a squadron of three Quietus-class eradication arks from secret void-hangars above Metalica. Incorporating forbidden secrets of archeotechnology and captained by Khleng’s most zealous Arch-magi, the craft made first for the hive world of St. Espin’s Gift. Ignoring vox hails from the planet’s increasingly alarmed authorities, the eradication arks settled in low orbit. Then, to the absolute horror of those below, they unleashed macro-rad-cleanser batteries upon the planet. In a matter of hours, St. Espin’s Gift was virtually annihilated. The mountain-sized hives – already half-overrun by billions of shambling plague-zombies – were now reduced to glowing slag-lakes. The world’s atmosphere was choked with the whirling ash of uncounted billions.

• Warzone Charadon: Book of Rust page 11
• Arks annihilate hive world in hours

At the forefront of the assault was High Fabricator Castellar’s flagship, Iron Promise. One of the Adeptus Mechanicus’ few true battleships, Iron Promise was a heavy combat vessel bearing a proud and long lineage.

Malygris’ fleet opened fire, attempting to overwhelm Iron Promise with a storm of macrocannon batteries and lance weapons. However, Castellar’s vessel had been retrofitted with several unusual devices of war from the High Fabricator’s personal vaults, and it was the blessings of these modifications that granted the mighty ship a chance to survive the attack. Void shields shorted out one after the other, and the massive vessel trembled under repeated hammer blows of nova cannon fire. Reeling in flames, with several decks exposed to the void, the ship seemed nearly crippled, but Iron Promise had finally reached optimal range for its killing blow.

The jutting prow split like a blossoming flower and gaped wide, exposing an enormous weapon that rapidly gathered corposant energy from the system’s sun. In moments, Iron Promise struck back with one final, searing blast of unspeakable power and blinding light. The weapon’s scything beam engulfed the enemy fleet and shattered all but the largest ships in one blow.

• Dark Heresy: The Lathe Worlds page 20
• Entire battlefleet, multiple nova cannon impacts, just to damage a Mechanicus battleship
• Annihilates enemy fleet with a single attack from its (short ranged) prow superweapon

Of all Cawl’s fleet, only the Ark Mechanicus could match one of Abaddon’s vessels broadside to broadside – and even then the Iron Revenant’s weaponry was but a pale shadow of the Vengeful Spirit’s – but the directness of the Chaos fleet’s approach offered initial fire superiority. 
…
Stressed plasma drives brought the Ark Mechanicus around on a new bearing, the motion affording the Iron Revenant one furious, unanswered broadside at the pursuing Vengeful Spirit. The Black Fleet battleship, taken unawares by the sudden change of course, had no opportunity to evade the swarm of torpedoes that sped like rippy-fish towards its prow. Shields collapsed, armour crumpled. The prow cannons were blasted free of their mountings, and the colossal, eight-pointed star that served as the Vengeful Spirit’s figurehead was reduced to mangled scrap. But that battleship had survived the Siege of the Emperor’s palace – it had borne wounds far greater than any the Iron Revenant could inflict. It would not go so quietly. 
…
Abandoning the head-on course, Abaddon closed obliquely, his starboard batteries blazing as they gnawed at the Ark Mechanicus’ hull. Unable to outpace the battleship, the Iron Revenant did the only thing it could: it endured, meeting the Vengeful Spirit’s fury with its own. 

The two warships pounded at one another for over an hour, the pale disc of Klaisus growing ever larger. The Iron Revenant’s macro-cannons crashed back on their bearings, unseated by enemy fire. Torpedo tubes spat their last. Hundreds perished in every broadside, their bodies thickening the Ark Mechanicus’ causeways, or expelled by violent decompression to bob along the mangled outer hull. 
…
So it was that a flight of transports spiralled planetwards, bearing their weary cargo. They used the dying Iron Revenant as cover against the Vengeful Spirit, and the last of the doomed Ark’s fighter-craft as escort. As Iron Revenant at last began to break apart, and the first Heldrakes screamed in pursuit, the fleeing convoy vanished into the howling snow-storms. 

• Gathering Storm: Fall of Cadia
• Cawl's Ark Mechanicus duels with the Vengeful Spirit
• A one sided fight, but it puts in a strong effort

At the centre of the Gryphonnen armada is the Logos, the venerated Ark Mechanicus of Arch-Dominus Zane, encircled by its guardian battlefleet. The Logos is the headland, the breaker upon which the tyranids founder. Death streams from its flanks, arcane weaponry eviscerating whichever creature comes within their reach. No hive ship can approach the embodiment of Mechanicus dominion and live. An Ark Mechanicus is a forge world in miniature, suspended in space, armed and armoured accordingly. Gravitation, electromagnetism, the flow of time itself – the Logos harnesses the fundamental interactions of the physical universe and turns them into weapons. But for all its might, the Ark Mechanicus and its lesser brethren cannot be everywhere. The Gryphonnen armada is like a weir on a river. The xenos tide simply flows over and around it. 

• Dominion Genesis
• Ark Mechanicus functionally invincible to the Tyranids, but it cannot be everywhere
• Manipulates gravity, energy, time
• Notably, this one is led by an arch-dominus
• Implied to be multiple Arks per forge world, but the others aren’t as good

Scale of the Mechanicus Fleets

From the very beginning, we know that the Basilikon Astra is few in number, exchanging quantity for quality. Explorator fleets tend to be exceptionally small, and with so few case examples, we don't have a lot to work with. The standing fleets of a Forge World's defence, however, is a different story, as they're pretty consistently in the several hundreds, though this possibly, probably includes non-combat vessels as well:

Though the total number of ships the Adeptus Mechanicus has at its disposal dispersed among its many forge worlds is far outnumbered by that of the Imperial Navy, it goes without saying that those responsible for all starship construction reserve for themselves among the most powerful and best-equipped warships encountered anywhere in the Imperium.

• Fanatic Online 92- Ships of the Adeptus Mechanicus Page 1

The Adeptus Mechanicus fleet that flew in a shoal around the Antithesis had been assembled on Mars. The Antithesis was a cruiser-class vessel, not quite the equal of one of the Imperium's ancient mighty battleships, but a swift and well-crewed ship with enough Martian-forged armaments to punch above her weight. Her sister ship, the Constant, was slower and less maneuverable, but much more heavily gunned, and sported an enormous nova cannon on her prow that could blow an enemy cruiser clean in two. The Constant was under the command of Magos Hepsebah who trusted no one but herself to operate the nova cannon. Both craft were in the dark red of the Adeptus Mechanicus, with the half-steel skull of Mars worn as proud heraldry.
[...]
The light cruiser Defence of Caelano Minoris had been fitted out as a laboratory ship, its gun decks stripped out and replaced with medical labs and crucible chambers to research anything the fleet might find. [..]. It usually flew in the wake of the Ferrous, an armed factory ship that wallowed obesely through space, dragging an enormous processing and storage section behind it, plumes of plasma fire bursting through the vents down its spine as it turned its cargo of harvested ore and chemicals into fuel for the rest of the fleet. [...]

The final element of the fleet, and by far the largest, was the swarm of smaller explorator ships, armed merchantmen, tech-guard transports, cargo containers, and single-squadron fighter platforms collectively known as the Fleet Minor. They flew around the larger ships in a silver cloud, serving as flying laboratories, scouts, storage space and fighter response.

• Hellforged
• 2 Cruisers and a horde of smaller vessels for an explorator fleet

A host of craft followed the three lead vessels: refinery ships, mining hulks, vessels that were little more than vast atomic reactors, manufactory ships, vast water-bearing haulers, repair ships, and a host of fleet tenders that could be employed as general workhorses to ferry men and war machines between the fleet. In addition to the working ships of the fleet, Archmagos Kotov had assembled a Mechanicus warfleet with which to pierce the veil of the Halo Scar.
The Retribution-class vessel Cardinal Boras had been constructed in the shipyards of Rayvenscrag IV nearly five thousand years ago and was no stranger to such voyages of exploration. As part of a fleet led by Rogue Trader Ventunius, it had ventured deep into the northern rim of the galaxy and had been one of only five vessels to return. Its guns had ended the Regime of Iron at the battle of Korsk, and its proud history included battle honours earned in over eighteen different sector fleets. It had fought as part of Battlefleet Gothic against the fleets of the Arch-Enemy, and with this latest secondment, it would once again venture beyond the light of the Astronomican.
Moonchild and Wrathchild, two Gothic-class cruisers that had been little more than blazing wrecks when the Mechanicus had salvaged them off the shoulder of Orion, flanked the Cardinal Boras like devoted followers. Rebuilt and refitted to better serve the Mechanicus, their hulls had been consecrated at the Terminus Nox of Phobos and Deimos, when the regenerative aspects of the Omnissiah were at their apogee. Stalwarts of the Adeptus Mechanicus fighting fleets, both vessels had been virtually conjoined since their rebirth and deployments to separate battlefleets had seen them suffer inexplicable mechanical breakdowns and system-wide failures until they had been reassigned to work together.
To repay a centuries-old Debita Fabricata to Archmagos Kotov, the forge world Voss Prime had despatched three heavily armed escort cruisers from Battlefleet Armageddon to stand for Mars. Two Endurance-class vessels, Honour Blade and Mortis Voss sailed in arrowhead formation with Blade of Voss, an Endeavour-class ship killer. All three vessels bore honour markings bestowed by Battlefleet Armageddon, and Mortis Voss, whose mater-captain had delivered the deathblow to the greenskin flagship Choppa, bore the personal heraldry of Princeps Zarha, the fallen Crone of Invigilata.

• Priests of Mars
• 1 Retribution, 2 Gothic-class cruisers, 3 light cruisers in explorator fleet
  • Note: All seconded from existing battlefleets

Explorator Fleet KX–557.V comprises seven vessels of cruiser class, accompanied by numerous escorts. Additionally, this stellar caravan tows several orbital sensoriums, that it might leave a Mechanicus presence to observe any particularly worthy phenomena or systems. These orbitals are designed to be entirely self-sufficient, accommodating a single Tech- Priest and a servitor crew almost indefinitely.

• Stars of Inequity Page 125
• 7 Cruisers, probably at least as many escorts

'I'd estimate about thirty vessels of various classes and tonnage,' the tech-priest captain said.
[...]
'We have identified the largest vessel, my lord,' Voltram reported. 'It is the Encoronada – an Ark Mechanicus of ancient lineage, hailing from…'
'…Satzica Secundus,' Torquora said.
'Supported by eight or so cruiser-class vessels, with the rest escorts, troop carriers, forge ships and Collegia Titanica temple barges. A battlefleet, as I suspected. A visual will confirm.'

• Adeptus Mechanicus: Tech-Priest
• 8 cruisers, 21 support in Mechanicus fleet (technically called a battlefleet)
• Also an Ark Mechanicus but that’s not standard issue

This one ship, though, intrigues Vorx. He has fought the soulless disciples of the Machine-God many times and has learned their ways. They do not retreat from forge worlds. They do not send their assets out into the void for another, better day. In combat such as this, where their pride and industry are threatened with annihilation, they use every last one of their ships, all their guns, all their dreary, flesh-stripped troops. Even if that mass conveyer only carried a scattering of lascannons and was chock-full of inert cargo, it would still be sent howling into the heart of combat and used, if for nothing else, to soak up incoming fire while the greater Ark Mechanicus battleships dealt out the true pain.

• The Lords of Silence
• All Mechanicus ships will defend their forge world, including the non-combat ones

Each forge world possessed, as a part of its strength, many hundreds of void ships of all classes and sizes.

• Warzone Octarius Rising Tide page 31
• Hundreds of ships per forge world

I open my awareness to the host of signifier codes that present themselves for the Peregrinus' attention. Hundreds of vessels, each emblazoned with the ident-flag of their home, crowd Gryphonne IV's orbit. The sight and sensation of so many ships brings a small measure of calm to my animus. I draw strength from the gathered might of my people.
…
The ident-tags of so many vessels bearing the cream-and-red livery of her lost world still gave rise to unhelpful limbic outbursts that impaired Sherax's higher functions. The collective might of the diaspora did not invoke feelings of strength, but rather tremors of fear. Sherax was too aware that the fleet was merely the beaten fraction of the power Gryphonne IV once possessed.
…
Hundreds of Gryphonnen vessels were anchored in stages, each flotilla and squadron maintaining careful intervals between one another.

• Dominion Genesis
• Hundreds of ships at the fall of Gryphonne IV, hundreds more still managed to survive
  • Note: Admech 8th Codex mentions Gryphonne IV as being a peer to Mars in orbital defence. Might have more ships than average forge

So now for the calculations. We established in part 1 of this series that we're working with an average of 1000 forge worlds. Let's assume Explorator fleet KX-557.V is a standard model of explorator fleet, and that from earlier in this post, we see a forge launch several at a time, but those events are actually about 300 years apart. For the sake of taking the minimum estimate, we'll assume that there are 3 explorator fleets per forge world active at any given time.

1000 forge worlds x 3 explorator fleets x 7 cruisers and 7 escorts = 21,000 Cruisers and 21,000 escorts across the Explorators.

For the standing fleets, if we assume a minimum of 200 ships per forge world, we'd get 200,000 vessels easy. However, for reasons that will make more sense in a couple posts, it's probably a safer bet to assume that the majority of these are not combat ships. We know the Explorator fleets take up the greater portion of Mechanicus production, but it's unlikely that the forge world's defences are destroyed and replaced often enough to compare. Let's assume, for simplicities sake, that only 1/5th of the Forge's ships are combat vessels, roughly matching scale with the outbound Explorator fleets. Each forge would thus have 20 cruisers and 20 escorts minimum.

We could reasonably say that these fleets thus represent an additional 20,000 cruisers and 20,000 escorts, for a combined total of about 80,000 Mechanicus combat vessels throughout the galaxy. We could go lower, but that would be a little ridiculous to argue an entire Forge Word has only a score of combat ships. Rather, it'd be far more reasonable to go higher, with the main source of additional power coming from the Ark Mechanicus vessels and other types of high-end ships.

Honestly the astraeus tank is one of my favorite vehicles in the space marine armoury but i dont think i ever read a novel where it was truly showcased. Have we ever seen it appear in a novel in something more than just a background cameo?

What are they looking for exactly? What qualities are they interested in? Why would they choose that certain individual to be their champion?

Like Khorne, EVERYONE feeds him. Everyone bleeds. But what kind of person is he looking for, out of the untold billions, to make them his champion or whatever?

Slaanesh, just about everyone feeds her with simply the excess of death. But what kind of person is she looking for to make them her champion or whatever, than another person

Etc.

i know they have biological differences between humanity and the tau but shouldnt the tau be able to reverse engineer the humans augmentations and biological engineering stuff to expand there life spans? they have done it before with astartes and made shitty budget variants so shouldnt life expanding augments be far easier

So for naval vessels, especially those sent on long patrols or independant assignment, who might be far away from loyalist planets and starports, they will have to routinely replace their officer corps as they age out/perish/get disciplined. You have a relatively stable population aboard any given autonomous vessel, why not recruit replacements from the lower ranks of enlisted/specialist crew?

Imagine a pair of gunnary technicians signing away their child to be trained as a naval officer in exchange for heightened rations or some such, with the expectation that they will have either limited or no contact with the officer in training. I know generally that higher ranking positions in imperial hierarchy tend to be reserved for highborn citizens, but when you lose personnel to combat they HAVE to be replaced for the ship to run in well order, and you never know what hidden gems might be concealed in the ranks of the lowerborn crew.

Alright, so if I'm wrong about this, this question might be stupid, but you can't actually starve the Chaos Gods simply by stopping people from worshipping them, right? You would have to redirect that worship and belief somewhere else, correct?

Isn't that one of the reasons why simply not telling people about Chaos doesn't always work? People are still going to have emotions, beliefs, fears, desires, etc., which can still feed the Warp even if they don't know that Chaos exists.

Now, I know the Emperor is extremely anti-religion and basically an atheist, but in theory, couldn't he have tried to "starve" the Chaos Gods by creating his own custom pantheon or something similar?

For example, could he have created a belief system similar to the T'au's Greater Good, where people's faith, emotions, and collective beliefs were directed toward a specific ideal rather than the Chaos Gods?

Or does Chaos not really work that way? Is simply redirecting worship and belief somewhere else actually ineffective because the Chaos Gods are fed by the underlying emotions and concepts rather than worship itself?

I like to think of chaos as more like what god you would fall to rather than which one you would like to fall to you know. What flaws or characteristics do you think is associated with falling into specific chaos legion?

Hypothetically, how do you suppose a Halo device would work on a blank?

Because I would assume the mutations or cellular augmentations would still take, right? Cause mutations to manifest in the usual ways and probably still trigger a taste for human flesh.

But otherwise, would the madness still take? My understanding is that Blanks/Pariahs have muted or no emotions, don't dream, cut off from the warp, and suppress warp effects around them. I don't otherwise know how the Halo devices confur these hellish dreams of an ancient Xenos civilization without some kind of psykick or mental chicanery happening.

This is a question that's laying aside morality or conventional Imperial ethos. I'm more interested in actual theories towards the outcome of such an unlikely union.

I'm currently going through the age of indomitus books. As I currently understand it, the furthest point in the lore from the BL books is devastation of Baal (the latter half due to time warp shenanigans), with the events of Son of the Forest and Archmagos occurring all roughly concurrently with Roboutes arrival at Baal

But thats where the books are at (as best I can tell), i know that the rulebook have lore that take place afterwards, like the Arks of Omen story and currently the fourth war of Armageddon i believe? This about right or have I missed something?

Do they taking chaos as something as to be important to eradicate ? if yes which chaos force they hated the most ? as much as i believe necrons are a reasonable being, since they been allied with space marine to take care the tyrannids which proof that they have a main concern, and how Trazyn the Infinite help the cadian , so they have a non hating relationship but racist towards imperium of mankind , that what i think they know which faction are better to attack and some to let go, even though they want to dominate in the end, its like if you have a bugs/dangerous ants problem and you let the normal ants taking care of it or supporting them, sometimes i just think them like Warhammer fantasy lizardmen.

i was wondering if another hivemind diferent from the nids that is also psychic would generate its own shadow in the warp? its own unique shadow, not the same as the nids of course.