Razors fine tuned into teeth on a chain continuously wind, the fine art of mechanical dentistry serving as a set of braces on an arm bar. It's that same rotating extension of blades that crosses the threshold between ashen air and All For One's mouth. A slap of steel delivers a blow to the featureless face, knocking the man's head to the side. A trickle of blood runs from the villain's torn lip; the fresh scar holds an uncanny light of resemblance to his successor's mark before it rapidly heals and no longer exists.
All For One's mouth shifts into a sneer as he turns his head back to face the beast that dare scratch him temporarily. And that's what it is. An abomination of chainsaws given life through fear. The same as him, a symbol of terror. Except with a loss of humanity. Like the bio-engineered Nomu, he took the beastial element of quirks and kept them to serve his sole purpose. So, for such a thing to defy him when he is the one who birthed its power enough to even be willed into existence – that infuriates him.
A howl of rage that carries skyward towards a crescent moon illuminates the night as fires are fanned out with whips of wind lashing around the two. An ancient quirk that shapes air into a sharpened state allows All For One to leave lacerations on the chainsaw creature. Akin to a powerful pine tree that's been hacked at, the beast bleeds green. A substance as thin but sticky as sap gradually leaks from its injuries.
The devils duel within the hazardous zone of cracked concrete. Burning pepper smoke curls outward from All For One's mouth, an aura of fumes that would sting any man's eyes and choke them out. A creature with a motorized mouth and gas powered eyes eats through it with an inhalement and an exhaust of equal blackened smoke. Darkness envelopes and encircles their collision.
This thing, no longer Izuku, pounds its chainsaw mounted fists against its opponent. But the body of All For One is impregnated with the very contamination that had unleashed it in the first place, rendering its blows ineffectual against a barrier of energy. With a chop and pivot of a punch, it shatters one of the chainsaws. All For One meets that mark with a strike that draws emerald blood.
A hammer blow to the metal skull of the chainsaw creature sends it reeling. Then comes a locomotive punch to its abdomen. All For One calls upon a variety of strength enhancing quirks and boosts them tenfold to match the monster's power. It's not quite a grudge match. There is much too little a lacking in the exchanging of blows for that to be the case.
Watching her short lived savior start to lose, Makima props herself up on one elbow to take aim with her other arm. With her undamaged hand, the woman points her forefinger and presses down on an invisible trigger with her thumb. Soot stirs within a shockwave of residual air currents and ignites as makeshift gunpowder. All For One gets struck through the chest, penetrated by a powerful impact.
"You..", the demon lord seethes through his teeth that are now stained with his own blood. If he had eyes as part of his featureless face, they'd bore into Makima's.
The chainsaw creature seizes the moment of distraction and also penetrates the villain, but with a chainsaw. The spinning blades shred the man's suit as it drives itself up and across All For One's torso. Red liquid meshes with green, casting a colorful painting of blood for them to slip on with their feet.
"You vile vermin!", All For One loses his cool and explodes with rage as much as he does sheer power. A detonation from within covers the field. All within the blast radius gets decimated in heat. A bright burning more consuming than simple flames seizes the site.
Mirio smashes through the last of the Nomu with his fist. It turns out the HPSC had been right about the hospital serving as a front for the monster lab. Right below thousands of patients was a basement where some would be taken to get reanimated by a mad scientist. Pure evil. That's what they're dealing with here. Mirio holds some satisfaction in knowing the old man responsible for their ill treatment is being arrested by Miruko.
Still, things aren't over just yet. When he tries tapping into the commlink in his ear, all he receives is static. It's hard to tell whether the causation is something interfering with the radio waves or if it's deliberate. Knowing he can't entrust things to Makima no matter the reason, he doesn't waste any time catching his breath. With a flourish of his cape, Mirio heads back to the hospital's surface so that he can go to the Kamino Ward.
"You've got a lid on everything here?", Mirio doesn't even pause to wait on hearing the answer as he walks past Crust.
"I think so", Crust turns to follow but is unable to keep up when Mirio zooms off, "Why- ?"
Left in a cloud of dust, the hero coughs and tries fanning it away from his face. "Kids these days..", Crust shakes his head before turning back around to assess the cleanup crew of cops, "I may just retire at this rate or join the police in handling the aftercare."
A wasteland, no doubt covered by a radioactive field, swallows Kamino completely. Striding through that devastation as though strolling around a beautiful park, is All For One. The villain's clothes are tattered and torn but his injuries are nearly closed and fully healed. As for the two who left those temporary marks, they lay by in puddles of their blood.
And then, the man of the hour touches down. Who All For One had been waiting for. "All For One..", All Might growls through gritted teeth in recognition of his old rival.
"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.
All For One devastates the area once more 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 Izuku's unconscious body, Izuku being still just a kid. He shields the 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 devil 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.
A news copter captures the chaos as it flies overhead, a 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.
It's still All Might versus All For One. The two titans clash time and time again. Their punches point at eachother but wind up drilling into the ground deeper and deeper.
All Might's arch nemesis attacks with another of his billion quirks, a bolt of electricity craning across the cracks in the ground. All Might leaps away before he can be made into an electrical conductor. But jumps right into a maelstrom of sewer water risen and controlled by All For One.
All Might fights the cyclone, using his signature Detroit Smash to clear the weather. The punch is powerful enough to help him land safely, but only momentarily. All For One is relentless, hurling steel beams and chunks of wrecked cars using a level of magnetism. The hero dodges and weaves, but also confronts some of the metal pieces head on. A front somersault to build up momentum and air pressure results in a California Smash. Scrap metal scatters the area.
All Might clears the football field distance between himself and All For One in an instant, winding up for a Carolina Smash. His hands in a cross position, he does a downward chop aimed for the villain's head with the intent to break his face further. But a seemingly invisible barrier puts a stop to that. "Nice try, All Might!", All For One says smugly before the forcefield expands and pushes All Might back.
Once again, the ground is uprooted and rock crumbles. All Might staggers back, huffing heavily as he tries to recover from the blow. The villain's killing aura weighs on the hero, a crushing pressure that makes his muscles sore and his quirk tingle in the base of his skull. Another shockwave crosses the expansion, and All Might braces for it. No time to dodge. He has to endure the force of the impact.
Suddenly, an explosion lights up the sky with the color orange. All Might turns his head to see the news chopper was struck by one of All For One's quirk attacks, back rotor burning as it spirals out of control. It's going to crash. All Might squats down, calf muscles primed for takeoff. But he's suddenly blindsided by something swatting at his face. It was in his peripheral vision so fast that he had no time to avoid it. A long limb with a claw at the end of it cuts across his right eye.
The hero cries out and instinctively places a hand over the wound. His one good eye sees that the limb that cut him recedes back into All For One's hand. "Keep your eyes on me, All Might", the villain continues taunting his opponent with a tone of amusement. All Might growls, vision in his damaged eye completely fading. It closes on its own, eyelids glued together by blood.
But All Might is only momentarily hindered. He forces himself to push beyond his limits and moves as fast as he can to intercept the falling helicopter. It's just about to collide with a weak structure when All Might catches it in his bare hands. The chunk of metal leans against the hero and makes his back arch as he tries to fight its momentum. The top rotor spins still, resisting All Might's grip.
While All Might is preoccupied with prioritizing a rescue, All For One begins prepping the fatal final blow. A culmination of powerful quirks transform one of his arms into a killing strike. Hypertrophy to enlarge his fist, another quirk that generates rivet-like growths, drill-like bone structures also applied, and several kinetic boosters combined with strength enhancers. Impact recoil and multipliers are added to the springlike limb quirk to top it off. The crucial combination aims for All Might to kill him with his back turned.
All Might is unable to see from his blindside what happens next. Preventing the impact and instead intercepting it, is the arrival of his successor. Mirio catches the giant fist mid swing, saving his mentor.
"Young Togata?!", All Might gasps with as much relief as he does shock.
"Looks like I got here just in time", the young blonde gives the older blonde an encouraging smile. Side by side, they're a bloody but cheerful duo.
But that's short lived. "I need you to get them out of here", All Might nods towards the bodies strewn around the site. Including Izuku Midoriya's.
"What about you?", Mirio hesitates.
"I'll handle All For One", All Might places a hand on his successor's shoulder before giving it a squeeze, "Now go."
Mirio nods. He leaves All Might to finish the fight while he handles the evacuation.
All For One chuckles, regarding Mirio with little care. He instead reacts to All Might's attack by intercepting it with his killing blow, picking up from where he left off. Their fists collide, sheer strength disrupting the crater they're in and sinking the surface even deeper. A sonic boom erupts from the power output.
Blood dribbles down from All Might's knuckles, his fist still grinding against All For One's. The amount of effort that he had to put into that punch drained him. Literally. Half of the hero's body has sunken in, muscles shrinking and steam wafting off his skinnier form. The time limit of his power is starting to reach its breaking point.
The reporter that the hero had rescued gasps when she sees what his true form looks like. The cameraman pulls back from the video recorder that he's holding, checking to see if what he's capturing is actually real. It very much is. All Might's true appearance is exposed to the world.
"D- Damn you..", All Might growls through gritted teeth as he continues struggling against All For One's fist.
"Ashamed that you can no longer sustain the symbol of peace you made yourself out to be? Well, have fear then.. Have fear. Because.. I am here", the villain speaks with the voice of the devil as he asks, "Where is your smile now, All Might?"
Within the fractured field, Tomura Shigaraki staggers along broken plates. Concrete crunches below his feet until he stumbles and falls to his hands and knees. Before him, he finds his master besting All Might. It's enough to make him smile despite what it took to achieve that sight.
"Perhaps this will provide some solace.. Nana Shimura has a grandson", All Might's one good eye widens, "And his name.. Is Tomura Shigaraki!" In that moment, the hero is just Toshinori Yagi, fragile and small. "And he's always HATED you LIKE ME!", the weakened symbol of peace starts to fall as he's pushed back by All For One's mixture of sheer power and this revelation.
All Might recovers, coughing on his own blood, but fighting back still nevertheless. His feet dig into the ground and he pushes against All For One's fist again. His body begins reverting back to its muscle form as he puts in overtime and denies the villain's claims, "You're lying!"
"This is too good to be a fabrication. You know it's true because it's the kind of thing that I'd do", All For One counters casually in contrast to All Might's desperation, "I've engineered the encounters between you and he like at USJ. You defeated him so soundly. You won, with a smile. So proud despite your ignorance! So sure of your own superiority!" Toshinori becomes more anguished with each sentence, feeling the truth behind the words like they're backhanded strikes. "Who is superior now?!", All For One laughs gleefully.
"HOW DARE YOU!", All Might yells back in the villain's face. Blood and spit splatters against the scarring.
All For One takes delight in his sworn enemy's rage, relishing in his anger and goading him to continue, "I haven't seen you this angry since I killed Na-"
"KEEP MY MASTER'S NAME OUT OF YOUR VILE MOUTH!", Toshinori's throat shouts in protest over his own yelling as much as his arm groans in pain against All For One's.
"You're too weak!", All For One activates another quirk that amplifies the power of his arm's force. Additional arms begin to unfold from the original limb, also pushing down.
"That's because I wasn't putting my back into it!", All Might yells back. He gives it all that he's got. Everything that's left in the tank. From one arm to the other in one crucial swing. A power transfer from his occupied hand to the other.
All For One had manipulated Nana Shimura's grandson into becoming a villain after killing her. He had stolen away that boy's life and now tried taking another with Young Midoriya's. The boy ridiculed for his quirk, called a devil, nearly set on that path because of this one true monster. No more. All Might vows that he'll never allow this man to destroy anyone's life ever again.
The whole color spectrum radiates from All Might's left arm to his right. Red arcs like an electrical surge, shifting to green and then sparking purple. His veins glow red and then yellow. He can feel the power of One For All's previous users culminating for this singular moment, "United..", he calls upon each of them to come together and make a decisive attack.
The arm holding All For One back breaks, becoming crippled, power leaving it in favor of the other. All Might's remaining arm bulks up, swelling in size and gleaming with energy. "States of..", all of the moves that he created are nothing compared to his finisher, "SMASH!"
All For One's face shatters on impact, his entire skull collapsing. The scarring that had healed reopens, muscle tissue and blood fresh. And the villain is carried down into the ground by All Might's most powerful punch yet. A cyclone comes forth, all of the wind channeling into that singular swing. Windows beyond the destruction site shatter from how far the sound carries when the hit connects. And All For One is buried into the ground, a grave just for him.
The last of One For All within All Might's system is gone. The red and blue suit of All Might hangs loosely from the skeletal frame of Toshinori Yagi, bloodied and tattered. He's just as worn down and bruised as the villain, the first time ever that the number one hero has been shown to sweat in combat. Ash and soot darken his face, splotches of dried blood crusting over his wounded eye.
But the hero's single remaining eye still stares ahead. Through the smoke. And at his successor. Toshinori's blue eyes meets Mirio's. From across the way, they look directly into one another's souls and acknowledge the damage that's been done without any exchange of words.
All Might moves, albeit slowly. He raises his unbroken arm up, high above his head. It's the stance he takes after every fight he wins. This is his final victory. The world sees him standing triumphantly.