Before the eggs hatched, the ghoul underwent one final removal. A declawing. The predatory organ that resides within the base of his back flourished in a frenzy. Each red limb flailed haphazardly, lashing out violently with a mind of their own. However, the futile attempt to preserve power and dignity did nothing but prolong the inevitable. The Kagune had been severed, cut through by an ability from one of All For One's stockpiled quirks, none of the doctor's tools enough to do the trick. Then, just as he had been forced to feed on his own fingers and toes, he was also compelled to devour his own tails.
The direct consumption of his RC cells implanted through those appendages trigger the stimulation of his quirk. Simultaneously at the moment the centipede's abnormal eggs hatched. Rather than spawning a plentitude of offspring, the insect had been altered genetically to produce somatic mutations from its germ cells. The ghoul's regeneration begins to coincide with this amplification and the formative stage of RC cells making a repeated web complete a more compact bond to a fixative state.
What erupts from the base of the ghoul's back is a new and improved predatory organ, a Kakuja armoring enveloping the flexible limbs. Each fold of black shielding hitches with pointed forcipules per segment, red liquid flow streaming beneath the protective covering. Trailing out from behind the ghoul are a collection of centipede tails, much bulkier than the previous Kagune. The base coverings click and close as they slowly twist around in an entrancing spin.
All For One grins ear to ear a white toothed smile, "Marvelous. Simply marvelous..", admiration in his tone over the success of the ghoul's experimented evolutionary cycle, "I do believe that you have outdone yourself, doctor."
The stubby scientist stares in equal fascination, captivated by the fruits of their labor. He hadn't expected the result to be so extraordinary. "I.. Not to undermine myself, but I should perform a few tests to ensure it all went accordingly.", he snaps out of his entrancement with the eagerness to have a closer analytic study of it.
But it's the room that replies, quaking in response. Dust dribbles from the foundational structure, weakening. A distant boom draws the doctor's gaze. The bar in which the underling villains reside is lit up like a holiday in red and blue lights. "It seems I have business to conduct elsewhere. In the meantime, continue your research.", All For One senses the situation without seeing it for himself. And he warps himself away, leaving the doctor alone with the ghoul.
The ghoul is curled in a ball, eyes clenched closed. That entire time, his body had been submissive. The coiling tails had been absent minded. The doctor turns his attention back to the boy, clearing his throat and pushing his glasses up his nose for a proper adjustment. The room is colder than it was before. The drop in temperature must be the reason why he's shaking so much. Surely, the boy can't be the reason, he thinks to himself. When the ghoul's eyes snap open, flaring red within dark voids, the doctor reconsiders.
At the bar, All For One makes his arrival known. Nomu are transported from their preservation tanks, no longer needed to be reserved for a time of usage. They vary in form, shape, and size. One with chainsaws for arms cuts through cops. Another tackles Endeavor. All For One walks through the havoc undisturbed, aura crossing the street and entering the bar. Kamui Woods, Edgeshot, and Vlad King fall to their knees immediately; the intimidating presence is enough to make them gag on their own blood.
Only All Might remains standing, though not without shaky knees. "All For One..", he growls through gritted teeth in recognition of his old rival. The sinister force wears a special mask to compensate for the need of life support machines, free to terrain the grounds.
"Come to kill me a second time, All Might?", the villain greets the hero with a presentative spread of his arms to show that he's very much alive. "Or shall I be the one killing you?", his fingers start to fold in preparation for an attack. All Might's eyes broaden in anticipation.
"RUN!", All Might tries to warn the others of just how powerful this man truly is. But it's too late. All For One devastates the area with a mere snap of his fingers. All the number one hero can do is make the judgment call to save one person. He chooses Bakugo, still just a kid. He shields the blonde boy with his muscular body and takes the brunt of the blow.
Blood seeps out from the corners of the hero's mouth, but he wipes it away to hide any signs of weakness. Then he spins back around to face the imposing suited figure of his arch nemesis. "You've gotten weak. You would have rescued everyone in time during your prime.", All For One taunts his rival with a tone of amusement.
Out from the corner of his eye, All Might can see the charred corpses of his allies. He yells in a fit of rage, charging the villain responsible. Wasting no more pretenses, the battle begins.
All For One spins his still raised hand, calling upon the raging fires surrounding the area with pyrokinesis. The flames flash focus to a centered ball, combining to make one big blast. The inferno burns brightly as it's launched at the hero. But All Might intercepts, pausing his rush to bring his own hands up and claps them together as hard as he can. The collision causes a shockwave, the gust of wind booming with a thunderous sound as the flames are dispersed.
That same air begins to vibrate before it can disperse like the flames. All For One utilizes the noise provided by All Might's power, weaponizing it and redirecting it as a sonic boom. The air pressure is an after shock of the sound being centered. All Might brings his hands to his ears next, covering them as tight as he can to block out the deafening noise. Even with that defensive move, sound seeps in and causes his ear canal to bleed.
The lack of fire and heat in the air starts to become known. The temperature drops rapidly, controlled by All For One. All Might gasps, a breath of condensation, his massive body beginning to frost over. Before it can completely be encased in ice though, he flexes his muscles and makes the hardening shatter.
His body freed up, All Might takes the opportunity to go on the offensive. He closes a hand into a fist and brings it down. His punch hits the ground, making it shatter like glass instead of concrete. The unstable surface would trip up anyone other than All For One. But for the villain, all it does is give him a proper push off to begin levitating. The monstrosity is now airborne.
All For One whips an arm back and then swings it forward, fingers jutting out in a crazed spiral. All Might leaps back and watches as they morph into a reptilian form. A giant serpent bares its fangs, striking just as quickly as a real snake. All Might catches the bite before it can close on him, holding back its jaws. The bite force isn't strong enough to rival All Might's power, but it does force him to dig his feet into the ground for a good grip.
The floor starts to grab onto All Might's legs, holding him just the same as he's fighting back the snake. He glances down to see the rubble shifting and covering his feet but he can't move without compromising himself to the reptile. He has no choice but to pull in separate directions with his arms, snapping the serpent's jaw. It slinks to the floor, dead. Then All Might rips his feet free.
Meanwhile, the ghoul is about to rip into the villainous doctor that caused him so much grief. A centipede limb crawls around the mad scientist, preventing his escape, pointed pedipalps stabbing him in places to keep him still. "Gigantomachia!", the doctor squeals in agony as he writhes with pain. His call for help reaches the radio he's plucked from his lab coat.
And the ground gives in. Then the ceiling. Then the walls. Everything collapses as something colossal rises up from the depths of hell. Debris rains down as the ghoul leaps from rock to rubble, doctor screaming in the centipede modified monster's grip the whole while. A body as jagged as the stone that's being broken climbs out from the enormous pit that's been made. The ghoul's limbs rattle in warning as the doctor is raised higher up.
"Let him go!", the living calamity booms through protruding canines. The scale of the equal monster is that of a skyscraper, towering over the buildings that haven't been demolished by its arrival.
The ghoul's response is tightening his hold on the doctor. The hardened limb wrapped around the scientist's waist constricts, snapping the man's spine. His lungs burst next, cutting off an inescapable scream from the doctor's blood gurgling throat. Sharp legs tear at the bent flesh, ripping it apart and exposing raw muscle tissue. Behind fogged lens, the doctor's eyes widen until they pop out of his skull.
Watching from close by, pro heroes Best Jeanist and Mt. Lady are appalled by what they're witnessing. The more experienced hero recovers first, stumbling over his words only slightly as he shifts his focus from the ghoul to the giant, "Th- That one looks like a job for you."
But the blonde heroine shakes her head, mouth agape as the ghoul sprouts more centipede limbs. Each additional appendage is larger than the last, dark armoring reminiscent of a dragon's scales. Risen up to the same height as the giant, the ghoul becomes his own imposing monster. "I- I don't think I'm the only one who can increase their size..", she murmurs out in horror of what's transpiring.
Earth plates shift from the blows being exchanged by combatants in the Kamino Ward. Panicked crowds topple over one another, the stampede stepping on the fallen and stomping them to death. Officers who attempt to evacuate the crazed civilians get knocked over and trampled on as well. Mayhem moves the screaming storm into traffic where cars are running people over or crashing into one another in an attempt to also flee.
A news copter captures the chaos as it flies overhead, reporter clinging to her microphone with a sweaty shaky hand. The pilot tries not to fly too close to the destruction for fear of being caught within the blast radius. The cameraman zooms in on the ground, lens focusing. Two figures are across from one another in one of the many craters that have been made.
All Might primes himself to take a mighty leap, planning to jump for his enemy. But pauses when a resounding roar encompasses the battlefield. The hero whips his head in the direction of what sounded like an angry scream, searching for the source. But smoke begins to envelope his surroundings. Another one of All For One's stockpiled quirks. With his environment concealed, All Might is forced to ask, "What was that? What did you do?", instead of seeing for himself.
All For One replies, "My latest creation. I think it's time you finally meet another renowned monster.", the tittering of a centipede's legs just as loud as the ghoul's war cry.