Daemonculaba

This article contains PROMOTIONS! Don't say we didn't warn you.

The Daemonculaba was the epitome of sickfuckery in Warhammer 40,000. It was a HOLY FUCK tier mad science project which, using stolen gene-seed, allowed for the creation of new Chaos Space Marines. It was first conceptualized by the Iron Warriors Traitor Legion, with the Warsmith Honsou (arguably the evilest villain in the galaxy) overseeing it.

So what made it so fucked-up and evil?

The Daemonculaba process began by rounding up some human females as slaves. Once corralled, they were shackled naked within iron-cages and force fed nutrients causing their bodies to widen and bloat to unfathomably grotesque proportions. Next, mad scientists called Savage Morticans (former members of the Adeptus Mechanicus' biological division corrupted by Chaos) utilized surgical and chemical techniques as well as Chaos magicks to radically alter the slaves' insides and embed them with stolen gene-seed. The 'birthing-womb' thus readied, an adolescent human male was then sealed within -- by performing what was essentially a 'reverse c-section.'

Days later, the candidate is reborn -- without any skin. Provided they weren't already dead, the candidate was then inspected to see if it was physically worthy to be a Chaos Space Marine. If it wasn't, it was literally flushed out the sewers to die in the barren wastelands surrounding the fortress laboratories. Occasionally though, the rejected creatures survived being cast out and many of these banded together as scavenger-hunters known as the Unfleshed.

If the candidate passed the inspection, flesh would be cross-stitched onto its body and its new life as a Chaos Space Marine would begin. The skin was harvested from the flayed bodies of human slaves; whose flesh had been painfully stretched to vast proportions before being removed while they were still alive.

The system could also use genetic material extracted from Iron Warrior corpses, which would then be implanted within the Daemonculabu.

As for the Daemonculabu themselves, if they happened to survive the birthing process, the cycle would days later begin anew, with them again being used as surrogate birthing-wombs...

And then Slaanesh is just looking at all this with interest, his eyes narrowed, and he says; "hmm, that's an interesting act, what do you call yourselves?" and Honsou sticks his chest out and goes; "The Aristocrats!"

Destruction

Varro Tigurius of the Ultramarines had a really horrible nightmare about the Daemonculaba, and Marneus Calgar ordered the then recently dishonoured Uriel Ventris and Pasanius Lysane to go and destroy it. With the help of the Unfleshed, Uriel and Pasanius succeeded, but Honsou was left filled with such rage that he started gathering an army to wipe out Ultramar.

This is still roughly twice as romantic as Breaking Dawn.