All for One didn't hesitate and shot his tendrils trying to impale Izuku but he ended up puncturing the water main beneath them. Thanks to that Izuku was able to absorb the water and metal to heal himself and his allies now with everyone up and ready to fight it would make it easier for him but he was wrong.

Izuku did his best to block all the tendrils aimed at him while using his sword while the other heroes were trying to deal any kind of damage to All For One but nothing was working until he opened multiple portals bringing all the villains and heroes from the bar hideout. When Shigaraki got up and saw Catalyst  he charged at him trying to decay him but he was met with a powered up punch by Izuku who was being surrounded by the other villains who were still with Shigaraki. AllMight then swooped in on the battlefield in order to assist with All For One taking most of his attention.

“How adorable, a master coming to save his student.” The two began going against each other with Izuku managing somehow with the villains. Fortunately Dabi was unconscious due to a prior attack against them, so the major opponents were the villains known as Toga, Spinner, Compress, Twice, and Magna. Out of all five, Compress was the more dangerous due to his ability to confine things into small marbles, that didn’t mean the rest were not a threat however. Toga’s skill with a small knife had nearly got Izuku quite a few times with Twice coming over to the and punch him. This was met with Izuku grabbing the villain's arm before swinging him into Toga before finding himself being sent towards Magna thanks to her quirk.

‘Gotta think of something, or I’m gonna go head first into that magnet.’ Trying to aim and stop the major problem, Izuku shoots a small beam at the enormous magnet Magna had to turn it to dust. With the still forward momentum, Izuku punched the lights out of the villain before looking at Compress and Spinner. He got into a fighting stance before charging at the two. They were cut off however by a shockwave nearly blasting the three of them away. The greenette boy looked at the fight between AllMight and All For One to only think one thing about the class. ‘This looks like a clash of titans instead of a hero and a villain.’

“Where are you looking boy!?” Spinner came at Izuku for him to dodge just in time to only get a small cut on his chest. “I’ve got everyone, we need to head out!” Compress attempted to make an exit with Izuku dodging a slash made by Spinner to charge at the masked villain. “YOU’VE GOT ANOTHER THING COMING IF I’M LETTING YOU ALL WALK AWAY LIKE NOTHING!” Compress attempted to turn Izuku into a marble with his hand for him to only dodge by grabbing his wrists and hoisting himself over Compress to give a strong ax kick to the head. Compress fell backwards with Spinner realizing he was outmatched. “COMMON GECKO! SHOW ME WHAT YOUR RESOLVE IS!” Spinner was knocked out however by Gran Torino kicking him in the face while making his entrance on the field.

“Good to see you again kid.” “Gran Torino, always a pleasure.” Their reunion was cut short by hearing explosions and noticing AllMight was barely keeping up with All For One. “Kid, what are you doing!?” Izuku jumped into the fight while running his hand on the destroyed ground to gain some life energy before passing it to AllMight. “Get your ass in gear number 1!” Izuku attempted a frontal attack with the formal villain before he raised his hand out to send a massive shockwave. Thanks to his still enhanced reaction time, Izuku dodged at the last second to keep going and knee the villain in the face, cracking his visor in the process. “I must say, you are a talented young man. Perhaps too talented.” All For One sent a shockwave to send Izuku flying back to only be caught by AllMight.

While he stood back on his two feet, Izuku’s hero costumes top half was blown off to have a nearby helicopter catch his damaged body on full view. Every man, woman and child in the country had seen the damage done to Izuku for most parents to either hug their child or pull them away from the screen all together. “My my AllMight, to think you’ve taken such a destroyed successor like this. I doubt he isn’t already on his deathbed like yourself.” All For One started laughing with Izuku getting angered. “So what!?” Everyone looked at Izuku as he walked over angered. “Just because I didn’t have something that everyone else had in the beginning, doesn’t mean I was weak. Just because you could hurt me easily, doesn’t mean I didn’t feel the pain.” Izuku now shouted the last part with everyone hearing. “AND JUST BECAUSE MY BODY IS SHOWN FOR ALL TO SEE, DOESN’T MEAN I WON’T KICK YOUR ASS RIGHT HERE AND NOW!”

Izuku ran up to the villain with his hand emitting a very bright light within the palm of his hand shouting "Maximum Decay Shot!" The attack seemed to have taken effect immediately; this had given Izuku an opening as he charged at All For One with his sword. When Izuku saw a pile of rubble he used it to leap at AFO but was caught by his neck and choked slammed onto the ground. "Boy announce your name to the world before you die!" The world awaited for the young man to say his name "I and the hero of Life Catalyst!" Suddenly AllMight charged All For One with a powerful barrage of punches shattering his mask which had cost AllMight his buff form "you're starting to be a real nuisance AllMight how about we show the world what you really look like!" When the dust finally settled AllMight was seen and the people couldn't believe that their symbol of peace was a skeletal looking man who was exhausted and on his knees with a little bit of power still in the tank. A woman who was trapped under the rubble of a building began to plead AllMight "Please AllMight don't give up! He suddenly felt rejuvenated as he saw Izuku transfer power to him. " I'll buy you the time you need to make it count." 

Izuku rushed All For One again dodging the tendrils while blasting decay bullets which began to annoy AFO that's when it led him to max out one powerful attack mixing multiple quirks "You'll taste my full power boy Air cannon, Spring like limbs, kinetic booster times 4, strength booster times 3, Rivets, Bone like spears. Now prepare for your death Catalyst!" AFO had sent his immense power to Izuku. In an attempt to block it, Izuku used his quirk in his hand to grab and siphon any and all power from the villain. Due to the rivets and spears in the fist however, they punctured Izuku’s hand to make him release a blood curdling scream while being pushed back. ‘I gotta stop him and make an opening.’

“I must say boy, you are handling yourself better than I expected. BUT THAT ISN'T GOOD ENOUGH! IMPACT RECOIL!” “AAAHH!” Izuku’s arm began to shoot blood from cuts in vibration from the shock of his own impact with the monster. He was at his end shaking in pain as his eyes began to dim. “Power is wasted on the likes of you. You are too weak!” Izuku started to see his life flash before his eyes. All the bullying, all the abuse, all the physical and emotional pain he’s suffered for almost a decade brought back to the surface to realize he’s been weak for a long time. “STRENGTH COUNTS FOR MORE THAN JUST HAVING POWER!” Izuku’s mind was brought out while see AllMight behind with all the power of OFA he had left in his fist.

“Power is only a means to get somewhere, but it does not mean one is strong or weak immediately. The strong are the ones that stand even when it’s hard to, to fight when it seems hopeless, and to be able to hold hurt even when they shouldn’t have to!” While hearing this, AFO attempted to evade with Izuku grabbing his arm with his second hand. “WHERE DO YOU THINK YOU’RE GOING!? MAX SIPHON!” Izuku pulled as much energy out of AFO while AllMight gave one final hit to end it. “So long AFO! UNITED STATES OF SMAAAASH!” The attack created a massive shockwave along with a tornado that had nearly pulled the helicopter above them recording the fight down. As the smoke cleared, two figures emerged. One was AllMight posing with his fist up to symbolize the fight was over, and the other being Izuku screaming to the heavens in both pain and adrenaline saying they won. Across Japan, everyone cheered for the duo’s victory with Ochako and Nejire praying to whatever god saved their boyfriend from meeting an end to such a monster.

Several hours later

As the cleanup began to meet it’s end with many pro heroes supporting the relief efforts, Izuku and AllMight watched as AFO was pulled away in a quirk nullifying straightjacket. However, something rather peculiar happened while he was being pulled away. “AllMight, what’s he doing?” Izuku began to panic seeing the villain become engulfed in darkness to make his features distort and take a different form. This image was one of a man with wild unkempt hair and freckles that formed a diamond as if connected. Once his eyes opened, an emerald green was shown before a panicked face was discovered.

“W-what’s happening!? Where am I!?” The man seemed extremely confused and scared as Izuku walked up. “W-who are you people!?” “....Dad?” As the man was still confused he began to yell out questions out of fear "Who are you?! Why did you call me dad?! My son was barely born!"