"Hm!"
A grunt of pain came out of All Might's mouth as his body was hurt internally. When he locked eyes with the injury, the muscles were fighting for their lives against the separation enforced onto them. He spent no spare moment before plugging his hand into the body to support the war.
'This meant All For One has done something.'
A shadow plunged All Might's location into darkness. All Might kicked off and deliver his newest punch he had been thinking a name for.
"United States Smash!"
All Might could feel the reaction coursing through his body, shaking every bones and organs inside. The struggle lasted for a minute before the shadow disappeared and All Might scanned again for the villain.
"All Might, below!"
He glanced down to finally notice his position had been brought closer to the ocean before a pair of giant arms rose up and tried to crush him. Using every bit of strength he had, All Might pushed his feet and back against the two sides, holding the enemy in place. The mech had switched to underwater combat mode and was dishing pile punker drive after drive in blinding darkness trying hurt the enemy but to no avail. Even the pilot was surprised seeing how the anti-quirk coating had not been able to neutralize the artificial lack of light.
With both the hero and the mech trying to break free, they barely noticed how the waves had silenced down and left a mirror surface reflecting pure dread.
'All For One must be lurking beneath this.', thought both of them.
The mech opened up its flare system and began lighting up the airspace above to provide lighting there. All Might slid down with the help of gravity, trying to reorientated his body. The sea in a radius of 10 kilometers around the two turned into superheated vapor before being controlled to induce a pressure bomb. All Might got both of them out of the area with three breaking-space punches.
"The mech is useless. I am joining you."
The pilot jumped out and landed on their feet, in their arm a bright spear. The armor they were wearing was fitted for ground and ocean combat so floating devices had been implemented on the soles. All Might's sense told him to block to the left and he did just that, barely able deflect the giant spear. With the need for searching, his quirk reeved up and All Might was able to see All For One. With his current form, the villain was more akin to a natural disaster or a god rather than someone with a villainous record.
And as the villain noticed them being able to detect him, a wretched smile spreading all across the face (?) appeared before gravity changed direction. The air in a large area was sent to space, an attempt to suffocate anyone in this arena. Without any material to push against, All Might's mobility was significantly affected and soon the fact would be rubbed into his face. Gravity changed direction, pulling him further along the passage toward space. For the pilot, after removing the helmet, she locked eyes with All For One before her entire body began to bleach out in All For One's perspective but it seemed All Might did not notice.
'Potent quirks, but a mere defective replica.'
Thought All For One as the woman rewind and restored an atmosphere of sulfur and oxygen. In the surprise of All Might, the woman twisted the surrounding space to the utmost limit, deleted the space between the villain and the hero, and then launched the latter to punch the former.
"How!?"
Thought All Might as just moments ago he was far away from All For One. The villain, he recognized, did not even bat an eye to the hero as he warped his way closer to the woman pilot before plunging the entire space was converted into a neutron star. All Might tried to rush in to save her, his hand and legs felt like swimming through molasses due to the density but with a space-breaking punch, he reached the center, a normal Earth-like atmosphere.
"All Might! We need to make a hole in the last barrier. All For One is toying with both of us. And bring the wreckage of the shi- Hmm!"
A bunch of hands spewed out from the plasma outside the sphere of influence of the woman and one of them would have caught her heart if not for All Might pushing her aside, sacrificing a section of the armor suit. Even after getting away from the attacked space, he was still feeling the heat.
"Give your best shot. "
All Might was brought to the highest possible location inside the space barrier, the final stretch before reaching space. Out here, the effect of the artificial neutron star had withered to nothing, rendering the place a relatively safe haven. There he found All For One already waiting for him.
'Lucky me.'
All Might punched with his might, the blow landed cleanly despite the surprise of the hero.
'How did I do it?'
The punch broke something, All Might could sense that. But not letting the hero to have time thinking about the situation, All For One used the spear he had let idle to broke a hole through the final spatial isolation barrier.
All For One used all of his arms to provide the thrust, not forgetting to use quirks to further strengthen the throw. With the weapon fueling his transformation being away, he should have been weakened yet the pressure All Might was feeling had not decreased but was actually increasing.
The hero spared no seconds, plunging his knee into one of the many eyes of the villain. He dug his way deeper one punch at a time and was stopped only by a layer of emptiness. There was nothing for his punch to collide on to impart force, there was no spacetime connection for him to punch through, a layer of protection impervious to any physical means.
While All Might was figuring out what to do next aside from going around and dealing damage to the villain, he noticed how the material had been becoming more and more compacted. The color was losing its definition as an implosion seemed to be occurring. All Might dug his way out again before All For One returned to the form of a naked human.
"This is perfect."
Whoosh!
Aenergy spear cracked the layer of emptiness protecting the villain, raising All For One's eyebrows.
"There seems to be a leeway for those with genetic similarities."
"Thunderbolt! Compression, EM!"
Shouted the woman as sparks of thunder flew out of her arms, a bolt of thunder before her chest. The wild nature of the lighting was stripped apart under the influence of a compressive force and electromagnetic manipulation. She sent the final product straight to All For One's face but even then her attempt of blinding him and breaking his barrier was stopped by the barrier itself.
"A requirement to shout out names to use stolen quirks. An inferior product from the Doctor."
All Might took the opportunity into his hands. He appeared above the villain before slamming him downward into various attacks the woman had prepared. The villain summoned back the spear he had thrown which was now impaling a large satellite responsible for the previous orbital strike. And with the distance between the weapon and its owner closing, All For One was shot in his shoulder, a bullet with blue and pink twist.
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A mid air combat sequence occurred at speed unobservable by normal eyes.
"You seems to be thinking much. How is my disciple?"
Said the general of the World Government as he disposed another set of All For One's clones. With a single kick, he obliterated the time connection holding the clones to the present, choosing to joke around with the villain.
"A wild dog, an artificial dog that is."
Commented All For One as he dodged the torsion forces from the reverse-timeline regions scattered around the secret base by separating and controlling his organs before reassembling them together. He did not forget to use a few small organs such as fingernails to get behind the general before manifesting a blackhole but the plan was stopped by a wall freezing time in place.
"How humorous. At least she is useful in pressuring your quirk storage.
"You think that subpar copy of me can do that?"
"Isn't that why you are not able to fend against my attacks, weakling? All your clones' quirks would take something from your quirk storage to use. You are aiming for my quirk and my intact body to use as ingredients for those thing you called Nomu to bypass that limitation."
All For one knew this was the information the future version of the general knew. But it seemed he had won. No need to gloat if there were still variables that could turn the tide.
'Udjat. Fire.'
All For One stopped the sudden attacks in his blind spots hidden by the general's time manipulation. One slashes after another cut grooves into the Alpes as the villain cleaved more and more personnel. His face was then grabbed.
"Focus on All Might. We have prepared something fun for you to play with."
A slam into the mountain range combining the force of thousands of iteration across spacetime into one pulverized the villain, the same as millions parallel world.
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All Might was thrown again and again across the battlefield and away from the clashing points where the woman and All For One was combating.
'What in the world is that.'
Everything, every moves, every thoughts, every strategies, was operating on levels faster than anyone he had every seen. His boosted body allowed him to keep up and provide some support before being teleported away again.
Just now he had punched a storm to swipe the torrents of hail, the size of the drop as big as a house, back to the sender. The woman teleported him closer to the villain to draw the focus away from her to attempt a breakthrough. The attempt was thwarted because she felt an attack coming from the space where she was at. All Might punched All For One in the face and drew some blood from the nosebleed but the injury was quickly healed and the hero was sent away. The hero struggled to steal the spear during the flight but it disappeared to dodge the grab before reappearing inside the villain's grip.
'This is just a stalemate.'
Two of them recognized that All For One was playing around with his toys but they could not do much. All Might had the strength but not the utility of multiple quirks. The woman possessed an arsenal of lethal quirks but her proficiencies with each of them was not to the level of All For One.
'But what is he waiting for?'
"All Might!"
A sun appeared just above All For One before plunging downward. The villain spent no time confronting the attack and just teleported away. The miss attack boiled the ocean above, leaving a hole as wide as a city in the water before the rushing waves struggled to fill back up the vacant volume.
"Endeavor! What about the inland?"
"I have torched the source of your monsters. Hey villain, your filthy tree is nice firewood."
'Someone who burnt their own future, a momentary burst of a dying sun. Not important but ... he is useful for some things.'
All Might dived down into the ocean as if sensing something his allies could not. Then steam columns exploded from the water surface. Explosion after explosion, but the final one was the most impactful, sending something twirling upward the sky.
Now they could see what was under the water, something tens of meters tall with muscles hard enough to only deform when facing All Might punches. Despite the injuries the thing suffered from, regeneration kicked in and it continued its exchange with All Might. All Might cleanly severed one of its arms before blankly saying.
"...Gigantomachia."