The Warp.
Regarding what the Warp truly is, the Imperium of Man has no definitive conclusion, the Necrons have no definitive conclusion, and even the Warp entities themselves do not necessarily know. Yuno had pondered this question throughout her long eons of devouring.
One day, after unexpectedly connecting to the network of another world, she finally learned the truth: even the creators of her universe weren't entirely sure what the Warp was. Upon learning this, Yuno felt a sense of relief.
"Stop her!" "We can't! Where is the Divine Envoy? Where is the Envoy?" "The Envoy is hanging around her neck!"
To an ordinary mortal, or even an Adeptus Astartes, a Daemon of Slaanesh is a significant threat. But to the Great Devourer—even if what was currently attacking was merely an avatar, and even if the opponent was a so-called Greater Daemon—it was at most a foe worthy of a little serious attention.
Yuno's physical form was gradually adapting. This body could withstand more power and achieve greater feats. She descended into the deep underground, into artificial tunnels where she witnessed even more acts appreciated by Slaanesh.
There were people with perforations all over their bodies, being injected with stimulants and then hung up in interconnected chains; as the number of connections increased, the pain they felt grew more intense. Others were scraping the flesh off their own bodies bit by bit, seeing how thin they could become while still remaining alive. Such acts of "performance art" were countless. The people of the Underhive used this so-called "art" to vent the emotions trapped within them.
Yuno actually couldn't understand it: if the Imperium didn't want its subjects to worship Chaos, shouldn't they make their lives a bit better? From the memories she had previously acquired, the life of an average person in the Imperium of Man was arguably worse than that of a slave in the other world. With a life like that, how could they not seek the shelter of Chaos?
Yuno pondered this as she casually slapped a four-armed Keeper of Secrets to death. A bellowing, upright fat pig, draped in the skins of many women and wearing a scarf made of their "frontal armor" around its neck, looked revolting.
"To waste food like this... I have found yet another reason to hate Chaos."
She continued forward. Eventually, she reached her destination: a massive, ancient altar used for summoning Daemons of Slaanesh. The altar was crafted from ornate precious metals and coated in fresh flesh and blood. Mad cultists were digging out their own veins bit by bit with knives, weaving these tiny human tissues into a crown placed upon the altar.
Yuno wasn't picky about food; after all, it was all going into the reclamation pools anyway. The number of people hidden in this underground gathering place was substantial, and at this moment, they all launched an attack on her.
"Boring."
She walked toward the altar. As the flesh of those cultists burst apart, she poured her psychic energy into it. A Chaos rift that the cultists had spent decades trying to open through countless sacrifices and murders was forced open by Yuno in an instant.
By using this point to confirm the location of the Warp, she then allowed her main body outside the galaxy to channel psychic power directly into the Empyrean. A swarm of Daemons rushed out, but they didn't find the physical world they expected; instead, they were met with a vast Shadow in the Warp.
Yet they did not retreat. Just as they were about to clash with Yuno, their supreme deity stopped them. Subsequently, the psychic will of the Great Devourer from the Warp arrived, forcibly carving out a space for the two to converse.
"Interesting."
Sinking into the Warp, Yuno saw a nebula of colors from which decadent, enchanting music drifted.
"Do not get too ahead of yourself."
The only ones who could communicate with Yuno via psychic link were those on the same level as her.
"You can actually communicate? I thought you were just a mindless madman who knew nothing. Also, though I am loath to admit it, your body actually arouses my lust."
Yuno looked coldly at that chattering supreme entity within the Warp.
"What have you come for, Great Devourer? Have you come to seek pleasure with me? I would be delighted to try it with you. You can be on top."
"Shut up, Slaanesh."
The tone of the colored nebula changed. Psychic energy churned, sending waves rippling through the entire Warp. "How do you know my name? Great Devourer, I truly must look at you in a new light."
"Tell me, Slaanesh. What do men usually like?"
A long silence followed. "Uh..." Another silence. The flowing movement of the colored nebula came to a halt. "Well... generally, they prefer large breasts, don't they?"
Yuno looked down to weigh her own size and continued, "But some people like smaller ones, right?"
"I think your size is quite appropriate... Are you out of your damn mind? Am I your best friend? Did you go through all this trouble to come here just to discuss breast sizes with me?"
Suddenly, the Prince of Pleasure realized something. "Could it be that what that bastard said was true? A transmigrator has arrived, and he happens to be your lover? Heeheehee, interesting."
Yuno met the gaze coldly. The Tyranids and Chaos were mortal enemies in their ecological niches. She had come here for two reasons: one was to understand how to love a person, and the other was to give Slaanesh a warning.
"It is not that rare an occurrence, Slaanesh. You had best not harbor any improper thoughts. He is a man who holds a grudge."
"If you and he don't mind, we could do it as a trio. I guarantee I can satisfy you both simultaneously."
"Enough talk, Slaanesh."
The Shadow in the Warp expanded rapidly, the Great Devourer's power spreading lightning-fast through Slaanesh's domain. "Do you wish to fight me? Then bring it on."
Simultaneously, the Warp fluctuations across the entire planet were dampened. The psychic projection from the Great Devourer outside the galaxy created a thin layer of the Shadow in the Warp. The Chaos forces across the entire planet were weakened to varying degrees.
Yuki sensed something strange. Yuno had woken up exceptionally early today; she seemed to be in a bad mood, perhaps because the war on Gorgon wasn't going well. But he didn't need to worry. Who could possibly take down the Great Devourer?
What he needed to worry about most was whether those fanatical Chaos cultists would summon Daemons when he made his move. Griffith hoped the matter wouldn't escalate, so they absolutely couldn't allow Daemons to appear on a large scale. That was why the squad of Battle Sisters had come.
Suddenly, Yuki had an idea. "Steff, I have a few extremely troublesome opponents over here. I'd appreciate it if you could lend a hand."
After sending the request, Yuki turned his attention back to his two guests. "Raziel, and Iron Face—want to make a bet?"
Raziel took a deep breath of the powder from his ring. "I'm in."
No expression could be seen on Iron Face's mask, but her voice was quite enthusiastic. "Excellent. I've been waiting for an opportunity like this."
The two most powerful gangs in the Underhive, along with the new gang supported by the Ecclesiarchy and reinforced by Battle Sisters, were now prepared to take this opportunity to make a massive fortune.