The League of Villains (
The rise of All Might brought about the end of the age of villains and All For One's reign. His subordinates were all defeated and imprisoned and All For One's body was destroyed by All Might.
To spite the Symbol of Peace and return villains to prominence, All For One raised Tenko Shimura into his successor. Tenko is the grandson of All Might's master, Nana Shimura. All For One knew that grooming Tenko into the villain Tomura Shigaraki would be the perfect way to strike All Might's pure heart.
All For One cultivated Tomura's malice and villainy, raising him to hate All Might. Tomura grows into a spoiled man-child who only desires to destroy because he wants to. Kurogiri acts as his aide for guidance but Tomura sees him as little more than a tool. Gigantomachia was also cultivated as one of All For One's loyal followers around this time.
Tomura Shigaraki wants to murder All Might so the peaceful hero society realizes that the world is still dangerous and violent. All Might becomes a teacher at U.A. High School, bringing a lot of attention to the school. This includes the media, who surround the school's entrance shortly after the big time faculty addition is announced.
Tomura hides behind the crowd of pressers and eventually destroys the school's defensive gate. This gets the media on school grounds and prompts the school's alarms to sound and sends the students into a panic.
Tomura uses this as a cover and steals the itinerary for Class 1-A. The schedule details All Might teaching Class 1-A at an off-campus training facility. The League of Villains gather around seventy petty criminals and All For One supplies a strong Nomu for their evil mission. The next day, Kurogiri warps all the villains into the U.S.J. and they begin their assault on the U.A. students.
Tomura and Kurogiri are disappointed to find that All Might isn't present. The former decides they should attack and draw out All Might. The Rescue Hero: Thirteen tries to evacuate the students while the Erasure Hero: Eraser Head takes on the crowd of villains at the central plaza of the facility.
Kurogiri sneaks by Eraser Head and confronts Thirteen with all the students. He announces that this is the big debut for the League of Villains and demands to know where All Might is. Eijiro Kirishima and Katsuki Bakugo retaliate but Kurogiri evades their assault and spreads all of the students throughout the facility. The League of Villains plan to split up the students and kill them in the different areas of the arena.
The League of Villains severely underestimate the U.A. students as they prove to be more than a match for the low-end criminals. Tomura studies Eraser Head's moves and attacks after finding his weakness. Together Tomura and Nomu crush the Erasure Hero. Kurogiri incapacitates Thirteen but Tenya Iida manages to escape the facility to recruit reinforcements from the main campus.
Kurogiri reports Tenya's escape to Tomura and becomes deeply upset. In his normal sadistic fashion, Tomura tries to leave a pile of dead students behind for All Might and the others to find when they arrive. However, All Might arrives first to save the day.
All Might saves Eraser Head and defeats the remaining petty criminals, leaving only Tomura, Kurogiri, and Nomu standing. All Might and Nomu clash, but the villains work together to ambush and trap All Might. All seems lost until the more powerful students in Class 1-A intervene. Shoto Todoroki, Eijiro, and Katsuki effortlessly defeated villains earlier and made their way to the central plaza to stop Nomu. Katsuki even manages to restrain Kurogiri and Shoto freezes Nomu. Tomura is impressed that the kids are strong enough to free All Might and turn the tide of battle.
Nomu recovers from the student's attacks, frees Kurogiri, and engages All Might again. This time, Tomura and Kurogiri are kept out of the fight because of shockwaves produced by the intense exchange of blows. All Might defeats Nomu with a display of awesome power and this sends Tomura into a tantrum.
Tomura and Kurogiri attempt to kill All Might after he's weakened by Nomu, but the Tenya returns to the U.S.J. with the other teachers. Izuku Midoriya buys All Might enough time for the teachers to intervene. The teachers defeat the recovering criminals and force Kurogiri to warp himself and Tomura away in retreat after Snipe injures Tomura. Before disappearing, Tomura warns All Might that his reign as the Symbol of Peace is coming to an end.
Kurogiri returns the defeated duo back to their hideout. Tomura tells All For One that All Might hasn't weakened and Nomu was captured. All For One reassures Tomura that All Might will fall and orders him to use this as a learning experience.
The infamy surrounding the Hero Killer: Stain rises and gains the attention of the League of Villains. Kurogiri confronts him on a rooftop in Hosu City and recruits him to their hideout. The Hero Killer is motivated to rid the world of false heroes and asks what Tomura's motivations are. Tomura simply answers he wants to kill All Might and this disappoints Stain. Stain believes killing is meaningless without conviction and prepares to cull the villains in the same manner he does the false heroes.
The villains come to blows and Stain pins Tomura to the ground. Stain informs Tomura that he's a weakling because he lacks real conviction. Tomura destroys Stain's knife and forces him to back off. He tells the Hero Killer that he may not have "real conviction" but he desires to destroy society because it praises All Might. Stain realizes that they both agree to destroy the present and explains he attacked to test Tomura's motives. Tomura demands he leave but Kurogiri claims he can be an asset to the League explains he attacked him to test his motives.
Kurogiri returns the Hero Killer to Hosu. The latter explains he must stain the streets of society with blood until people realize that Heroes should not receive payment or glory for their actions. Kurogiri confirms the crime rates have dropped wherever he has slain false heroes. Stain leaves and Tomura mocks his work. He doesn't believe they can work together and decides to destroy the Hero Killer. Irritated, Tomura requests three Nomu's from All For One and has Kurogiri warp them to Hosu City.
The Nomu incite chaos across Hosu and Pro Heroes respond to the threat. Lower level heroes prove no match for the Nomu as they terrorize the city. Gran Torino and Enji Todoroki arrive in the city and combat the Nomu. Together, they defeat one of the Nomu and Endeavor takes on the remaining two alone. He rescues the weaker heroes from the Nomu and burns the larger of the two Nomu's head off. The other escapes and attacks Izuku, who just defeated Stain alongside Shoto and Tenya. Stain regains consciousness and kills the remaining Nomu, upsetting Tomura.
Tomura's plan was to use the Nomu to steal Stain's infamy so that no one remembers him. His plan completely backfires as the next day Stain becomes the talk of the entire country while no one speaks a word of the League of Villains. However, All For One had planned for this. Stain's powerful ideology becomes a headline that inspires villains hidden in the shadows to come out of hiding. They all move toward the association rumored to involve the Hero Killer, the League of Villains.
A criminal broker named Giran capitalizes on the League of Villains' newfound fame and recruits people to their cause. He recruits Dabi and Himiko Toga to the League's hideout and introduces them to Tomura. Tomura stubbornly refuses the new recruits and attacks them. Kurogiri stops the fight and sternly reminds Tomura their group needs to expand.
Tomura storms out and goes to the Kiyashi Ward Shopping Mall. Kurogiri knows Tomura has been humbled twice and needs to grow up. Tomura mulls over why society can smile thoughtlessly thanks to All Might even though the world is so dangerous. He confronts Izuku at the mall and asks the difference between himself and Stain.
Izuku reveals that Stain had real motives and didn't destroy for no reason, and he like most heroes he was inspired by All Might. Tomura makes the connection that he hates Izuku and Stain both because of All Might. He escapes the mall and finds his new conviction. Tomura decides to use Stain's ideology as a stepping stone for his new convictions: to destroy not only All Might but all of Hero Society.
Tomura Shigaraki develops into a real leader with actual conviction. He takes charge of the League of Villains and brings in powerful new recruits that have all been inspired by Stain. He decides to enlist strong villains instead of petty criminals and plans to bring down the pillars of hero society, U.A. and All Might.
All For One gives Tomura the location of an upcoming training camp for U.A. students. Tomura establishes the Vanguard Action Squad and sends them to attack the students with the intention of capturing Katsuki Bakugo. Katsuki has publicly displayed an angry and violent temperament that matches that of a potential villain. If the villains can capture a U.A. student and bring them to their side, they can deal a fatal blow to U.A.'s reputation. This will be their first major assault against hero society.
Dabi leads the operation with ten elite villains that make up the Vanguard Action Squad. They attack the third night of the studentsl Quirk Training Camp. Dabi orders his allies to take down the heroes from the pedestals and destroy the students' sense of peace. Dabi burns the forest while Mustard fills it with poison gas. This keeps their meeting point a secret while cornering students inside the forest at the same time.
Muscular, Moonfish and Mr. Compress look for Katsuki. Magne and Spinner fight the Pussycats and Twice distracts Eraser Head and Vlad King with doubles of Dabi  to prevent the Pros off from protecting the students. Nomu is released to incite chaos, Mustard maintains the cloud of toxic gas, and Himiko is tasked with collected three different blood samples.
Moonfish, Muscular, and Mustard are all ultimately defeated by the students. Mr. Compress successfully captures Katsuki and brings him to the rendezvous point. Izuku, Shoto, and Mezo Shoji nearly stop them, but Kurogiri retrieves the conscious villains and warps them to safety. The villains return to the hideout with Katsuki after successfully completing their mission.
Having successfully kidnapped a U.A. student, the League of Villains deal a crushing blow to U.A.'s reputation and hero society as a whole. Katsuki is brought face to face with Tomura and they discuss the current state of affairs. Spinner tells Katsuki about Stain's ideology and what it taught the villains. Tomura adds that hero society is broken and claims that diminishing the hope behind society is why the villains are winning. Tomura suggests that Katsuki join the League because he likes winning.
The League of Villains is comprised of members who have been suffering while everyone else has peace. They believe Katsuki's allegiance doesn't align with his core values. Tomura has Katsuki freed from his bonds but the tenacious student immediately attacks Tomura and explodes his face. Katsuki refuses to join the League of Villains because he wants to be a hero who wins just like All Might.
Instead of throwing a tantrum like he normally would, Tomura shows his growth and calms everyone down. He puts his mask back on and asks All For One to lend him the power to force Katsuki into submission. They're interrupted when suddenly a pizza delivery arrives at their door. All Might abruptly breaks into the hideout and Kamui Woods restrains all the villains at once with his Quirk.
Gran Torino knocks Dabi unconscious and Edgeshot lets the Police into the hideout by unlocking the door. Within just a few moments, the Heroes have successfully counter-attacked against the League. Gran Torino reveals the Police's investigation into the League of Villains turned up not only their hideout but most of their member's identities (except for Tomura, Dabi, and Kurogiri).
Tomura mulls over the villain's desperate situation and orders Kurogiri to summon the Nomu. They're surprised when none are transported from the factory. Tomura tries to use Kurogiri's warping ability again but Edgeshot knocks him unconscious. Mt. Lady breaks in the Nomu factory and Best Jeanist leads the team inside. He uses his Quirk to restrain all the Nomu and the heroes successfully take control of the hideout.
All For One is forced to reveal himself in order to rescue his protege. He appears at the Nomu Factory and attacks Best Jeanist's team. He uses his own Warping Quirk to warp the Nomu to the main hideout. The Nomu appear from portals made from black liquid and attacks All Might's team. All For One transports the villains and Katsuki to himself. He reassures Tomura that he can start over and his plan to overthrow hero society will eventually succeed. All Might chase after the villains and arrives at the scene to confront his arch-nemesis.
All For One uses Forced Quirk Activation on Kurogiri and orders Tomura to escape with his allies and Katsuki. He holds off All Might while the villains try to capture Katsuki again. A rescue team made up of Izuku, Shoto, Tenya, Eijiro, and Momo Yaoyorozu intervene and help Katsuki escape from the battlefield. Tomura is fiercely annoyed that Izuku once again interferes with his goals.
Compress, Twice, Spinner, and Magne try to recapture Katsuki but Gran Torino knocks them all out. All For One uses Magne's Quirk to send all the villains through a warp gate so they can escape. Tomura knows All For One's body is too ruined to combat All Might and is dismayed when he's forced to leave his master behind.
All For One takes on All Might and Gran Torino alone. He warps Gran Torino in the path of All Might's punch and hits him with Impact Recoil. All Might is able to save Gran Torino before the villain kills him. One For All taunts his nemesis about holding back. At this point in the battle, much of Kamino Ward has been destroyed by All For One. Heroes and emergency services have dispatched nearby to rescue civilians.
All Might can't risk allowing the shockwaves from their battle to injure any more people. The Symbol of Peace is enraged by the evildoer's words and uses the strength he has to crush All For One's mask with a powerful smash. All For One survives the attack and compares All Might's aggravated response to his master Nana Shimura.
All For One uses his destructive power to weaken All Might and reveals his weak form to the entire world. Even so, All Might remains steadfast. In order to deal a blow to the Symbol of Peace's heroic pride, All For One reveals the truth about Tomura being a relative of Nana Shimura. This crushes All Might until he's reassured by other Heroes and civilians watching the No. 1 Hero protect them. All Might regains his vigor and charges up his arm with the last embers of One For All.
All For One realizes that All Might is on his last legs and prepares to deal the final blow. He finds it unfair that after Tomura has worked so hard to chip away at Hero society. Edgeshot and Endeavor interfere and buy All Might enough time to prepare the final embers of One For All. All For One blows them all away and activates his perfect combination of Quirks.
Light and darkness collide and the final confrontation begins. All For One recognizes that All Might is using embers of One For All left over from passing it to Izuku. All For One is even able to identify Izuku as the new torchbearer. All Might continues to fight because he has to raise Izuku as Nana Shimura did for him. He switches his power between arms so All For One will miss and then smashes his mask with a left hook. All Might defeats his arch-nemesis with his ultimate move: United States of Smash!
All For One is defeated and transferred to Tartarus Prison. Despite being defeated, All For One is excited because he knows that this will allow Tomura to grow into a villain that can take the reigns as the new king of darkness. Tomura Shigaraki and his allies regroup and swear vengeance for their fallen master 
Tomura embraces his role as the boss of the League of Villains and restarts their operation. Himiko Toga is assigned with infiltrating the Provisional Licensing Exam and obtaining a sample of Izuku's blood. She drugs Camie Utsushimi and poses as the second year Shiketsu High School student for the test.
During the first phase of the licensing exam, Himiko targets Izuku and tries to eliminate him after Class 1-A gets separated. Himiko overwhelms Izuku with her ability to hide her presence. When students from rival schools interrupt, Himiko transforms into Ochaco. She nearly eliminates Izuku but he sees through her disguise.
They fight to a stalemate that's eventually interrupted by Izuku's classmates. Himiko manages to scratch Izuku's face and gets a drop of his blood. Himiko is one of the last participants to pass the first phase of the exam. Having accomplished her mission, Himiko drops out of the exam's final phase and escapes without anyone ever becoming the wiser.
Mr. Compress calls Himiko and warns her not to get caught. Himiko claims she's never been caught, sheds her disguise, and confirms she got a sample of Izuku's blood.
All Might's retirement following his battle with All For One has dealt another crushing blow to hero society. Endeavor becomes the symbol of a weakening society and villains rise up in the wake of a new era for villains.
The League of Villains spread out to conceal themselves from the Police and to recruit new allies. Giran contacts Twice and asks for Dabi's location because Tomura wants everyone to meet again. Dabi is out looking for recruits, but refuses to take in low-end criminals and cremates them instead. Magne meets with a friend and Spinner disguises himself in plain sight.
Twice encounters Overhaul and his followers dealing with a group of rambunctious thieves. He believes Overhaul is the perfect kind of crazy to be recruited to the League of Villains. Twice talks with Overhaul and the latter agrees to meet with the League. The League of Villains (except for Dabi and Spinner) meet at an unmarked warehouse where Twice introduces Overhaul to the others. Tomura is impressed Twice found such a good recruit.
Overhaul mocks Tomura's statement and Magne questions who he is. Tomura reveals All For One once showed him a picture of the young Yakuza Captain of the Shie Hassaikai. Himiko asks what a Yakuza is and Compress explains they are relics from a time before the age of heroes. Magne asks if Overhaul is riding the high after All Might's retirement.
Overhaul reveals that the fall of All For One is more significant. Yakuza elders revered and feared All For One but they've learned of his recent downfall. Overhaul tells the League of Villains that there is no king of light or darkness anymore. Tomura claims that he will become the next king of evil and Overhaul asks what his plan is. The Yakuza claims that power is useless without a plan and Tomura wasted first-class pawns like Stain, Muscular, and Moonfish in the past.
Overhaul asks the League of Villains to come under his wing but Tomura tells him to leave. Magne refuses to submit to Overhaul and attacks. Overhaul defends himself and brutally murders Magne with his Quirk. Compress rushes into action but he's shot with a Quirk Nullifying Bullet and his Quirk doesn't activate. Overhaul blows Compress's left arm clean off.
Tomura attacks but one of Overhaul's followers sacrifices himself to protect his master. Overhaul's other followers burst into the hideout and the villain asks that everyone calm down. He claims it's unfortunate the meeting turned hostile and says they're both down a member. Twice and Himiko want to avenge their allies but Tomura orders them to stand down. Overhaul leaves his card and asks Tomura to contact him when his group has relaxed.
A few days later, Tomura calls the number and tells Mimic that he wants to have another meeting. A black communion between the Shie Hassaikai and the League of Villains commences. Tomura meets with Overhaul and his gang after being lead through their underground base. Tomura sits down with his feet up and immediately announces that if the League should join forces with Yakuza, it will not be under the Shie Hassaikai instead, they will be equals.
Tomura's second condition is that Overhaul shares the details of his plan because the League won't be involved in worthless schemes. Tomura reaches into his jacket and insinuates he has an idea about the Yakuza's plan, but Chrono and Mimic threaten him. Tomura is mostly unaffected and demands compensation for the death of Magne, claiming a throwaway shield could never match the value of Big Sis. Overhaul calls off Chrono and Mimic, and Tomura takes the Quirk-Killer Bullet that was used on Mr. Compress. He asks if their big plan has anything to do with the drug.
Overhaul shares the details of his plan to eradicate Quirks using Quirk-Killer Bullets. He invites Tomura to play a game of Shogi but he refuses. Overhaul explains the fun of Shogi is using the opponent's pieces and asks that Tomura lend him Himiko Toga, Twice, or Kurogiri because he doesn't want them moving about. Tomura initially refuses because their Quirks are essential to the League of Villains, but Chisaki insists that the League return the favor since Chisaki did reveal his entire plan.
Tomura meets with his allies and reveals their alliance with the Shie Hassaikai. This doesn't go over well at all with Twice or Himiko. Twice feels extremely guilty for getting Magne killed and pleads for Tomura to realize he's still human. Toga announces that she joined the League to feel good and be like Stain so that the world is easier to live in. She lifts her knife to Tomura and demands to know why she has to do such an unpleasant thing.
Tomura surprises everyone and takes off his mask. He claims they have to do this for the sake of the entire League because the Shie Hassaikai is looking to overtake them as the pinnacle for villains. They haven't viewed them as equals and Tomura tells Twice he needs to take responsibility for what happened. He trusts Twice and Himiko to do what they think is best for the League in this situation.
Despite their misgivings toward Overhaul, Twice and Himiko become temporary Yakuza. Overhaul apologizes for killing Magne and asks that the new recruit share their abilities up front. Both Himiko and Twice explain their Quirks and Shin Nemoto uses his own Quirk to make sure they don't plan on betraying the Yakuza. Overhaul asks that as wanted criminals, both the temps stay on base for the time being.
When the Heroes invade the Shie Hassaikai's hideout, Overhaul orders his temporary villains to help the Eight Bullets cover his escape. Twice and Toga are forced to work with Mimic on taking down Sir Nighteye's Squad. Himiko takes on the Lock Down Hero: Rock Lock and ambushes him alone. Rock Lock disarms Himiko and appears to defeat her, only for it to be a clone. Himiko gets behind Rock Lock and stabs him. He asks what the League of Villains is doing but Himiko claims she's a Yakuza now. She incapacitates the hero and takes on his appearance.
Izuku and Eraser Head confront her but she tricks them long enough to close in on Izuku. Eraser Head destroys her disguise and Izuku recognizes her, much to Himiko's pleasure. Eraser Head gets her away from Izuku but she stabs him and retreats. Twice takes on Sir Nighteye but his clone of Kendo Rappa is destroyed and he's forced to retreat as well.
Himiko helps Twice calm down after his defeat and they recall Tomura's encouraging words. They decide that they're going to do what they feel is best and decide to destroy the Yakuza from the inside. This angers Mimic but the villains betray him and use the Heroes to defeat the "useless" Yakuza.
They to scheme to kidnap Eri, the centerpiece of Overhaul's plans. Himiko wants to kill Overhaul herself but they decide to use the Heroes to realize their ambitions. They hope that the Yakuza and the Heroes will destroy each other. Himiko takes on Izuku's appearance and leads Ryukyu's Squad right to Overhaul.
Twice and Himiko are unable to capture Eri, but they help the Heroes eventually defeat Overhaul. Following the downfall of the Shie Hassaikai, Himiko and Twice escape the area and contact their allies. They inform them that Overhaul is being transported to a villain hospital via a freeway. Tomura, Dabi, Compress, and Spinner attack the convoy to get their revenge against the Yakuza.
The Sand Hero: Snatch tries to fight off the villains. Dabi and Mr. Compress work together to kill him while Tomura derails the rest of the convoy and Spinner acts as the getaway driver. Tomura confronts Kai directly and reveals he has plans for him worse than death. Compress gets his revenge by removing Kai's left arm and then Tomura cuts off the right one. They steal the Quirk-Killer Bullets and Tomura mocks Kai's life's work. The League of Villains dramatically exit the scene of chaos and Tomura claims that they're all going to be the next kings of darkness.
Meanwhile, Kurogiri searches an unspecified mountain range for a certain recruit. He's caught by Gran Torino and the Police after making himself too noticeable. Kurogiri reveals he took that risk to make contact with Gigantomachia, a loyal follower of All For One.
The League of Villains develop a powerful new Nomu that possess intelligence called High-End. The newly established No. 2 Hero Hawks claims he wants to join the League of Villains. He meets with Dabi and they plan for a Nomu to attack a factory near the coastline. Hawks agrees to send a random hero to test its abilities. However, Dabi changes the plan and orders High-End to attack Hawks and wreak havoc in the middle of the city.
High-End attacks Endeavor and Hawks while they're meeting at lunch. Endeavor takes on the Nomu while Hawks evacuates everyone with his feathers. Endeavor deduces that High-End all the black Nomu is a special type that all feature Super Regeneration as one of their Quirks. Not even Endeavor's Super Moves are enough to put this Nomu down.
High-End produces reinforcements for itself to hold off the weaker heroes and focuses on its objective to fight the strongest. Endeavor realizes that High-End is semi-intelligent as it even figures out his Quirk's drawback. The Flame Hero pulls out all the stops and blasts High-End with his ultimate move: Prominence Burn. However, not even the high powered heat laser can bypass the Nomu's healing abilities.
High-End tore its head off before getting blasted and used that to evade the attack before regrowing its body. It attacks Endeavor and cuts out his eye, appearing to defeat the new No. 1 Hero. Disappointed, High End asks if there is any stronger hero willing to challenge it. 
Endeavor refuses to stay down despite the power gap between him and the Nomu. Endeavor's tenacity inspires those watching as he proves why he can be the new symbol of peace. Hawks uses his wings to give Endeavor the power to rise like a Phoenix and match High-End's incredible speed. Hawks takes Endeavor high into the sky where he can unleash the full fury of his flames. Endeavor lodges his fist into High-End's mouth and burns the beast to death with a Plus Ultra Prominence Burn. Endeavor is victorious and the world looks on with hope at its new No. 1 hero. Suddenly, Dabi spoils the celebration and confronts Endeavor and Hawks by himself.
Endeavor recognizes Dabi as the man who murdered Snatch but Dabi ignores him and surrounds them in a wall of blue flames. Dabi wants to speak to Endeavor directly and attacks the top two heroes. Mirko interrupts the battle and forces Dabi to retreat, but not before the flame villain leaves Endeavor with an ominous message. Kyudai Garaki warps Dabi away and the heroes are victorious.
Dabi and Hawks meet afterward and discuss how the plan totally went off the rails. Dabi reveals he still doesn't trust Hawks and won't let him meet Tomura yet, but promises to contact him again in the future.
One month prior, during the time of the new Hero ranking announcements, the League of Villains wiped out a cult of anti-abnormality bigots known as the Creature Rejection Clan. Spinner becomes impatient, as the League is failing to bring Stains dream to fruition as Spinner believed they would.
The League is confronted by All For One's bodyguard, Gigantomachia. All For One's doctor used a small Nomu to teleport the League members to his lab. The doctor tells them that if Tomura can make Gigantomachia accept him as his new master, then the doctor would give the League access to incredibly useful resources. The doctor then uses the Nomu to warp them back to where they were.
After a month of non-stop combat with Gigantomachia, the League had yet to make any progress whatsoever. Around that time, a group known as the Meta Liberation Army, a group that opposes Quirk restriction laws, kidnapped the Leagues underworld broker, Giran. The Army contacted the League and told them that if they wanted to rescue Giran, they would have to come to Deika City and fight there way through the ranks of the Meta Liberation Army. The League was also told that if they refused to come, then the Army would send their current location to a number of top Pro Heroes.
The League decided to go, knowing that a sleeping Gigantomachia would be able to quickly track them down upon waking. The plan was for Gigantomachi to wipe out the Army and for the League to take down the exhausted Gigantomachia afterwards.
Upon arriving at the city limits, the League was guided by a Pro Hero who was in league with the Army. Once they were far enough in, the League was ambushed by the cities entire populace, all of whom were Army members.
Himiko was confronted by Curious, one of the armies top commanders. Curious, being a journalist, questioned Himiko on her origin story. Himiko, on the brink of death due to Curious' explosion Quirk, underwent a Quirk Awakening, allowing her to use the Quirks of the people she transforms into. By transforming into Ochaco Uraraka, Himiko used Zero Gravity to make Curious and her subbordinates float, then released them, letting them fall to their deaths. Though Himiko was victorious, she was pushed to the brink of death; so she found a garden shed and hid in there, hoping to wait out the battle.
Twice later found Himiko and prepared to give her medical treatment, but was ambushed by duplicates of himself, created by the puppet Quirk of Skeptic, another one of the Armies top commanders. The Army hoped to capture twice, hoping that he could clone the the Armies supreme leader in the event that something happened to him.
While Skeptics puppets were trying to restrain Twice, the Villain received a broken arm, confirming for him that he was the real one and not a clone as his past trauma had caused him to question. Twice had regained the confidence in his ability to duplicate himself. Twice began creating clones of himself, who made clones of themselves and so on, creating a literal one man army. This gave the original Twice the opportunity to give Himiko medical attention.
Meanwhile, Dabi was confronted by Geten, one of the Armies most powerful fighters; and Tomura was utilizing a previous unknown aspect of his Quirk: spreading the disintegration effect beyond what he had touched, allowing him to kill multiple enemies at once.
The Meta Liberation Army was beginning to lose hope, but Trumpet, the last of the top commanders, used his support Quirk to strengthen the Army members. Around that same time, the doctor woke Gigantomachia, and the behemoth sped off in search of the League.
A Twice clone made it to the tower where the Armies supreme leader was observing the battle and where Giran was being held. The Twice clone created duplicates of himself and the other League members. But the supreme leader dealt with the fairly easily using his power storing Quirk. At that moment Tomura reached the out side of the tower and disintegrated it.
The supreme leader survived the fall and engaged in battle with Tomura, using a greater level of his Quirk. By that time, Gigantomachi had arrived and began destroying everything in his path.
The supreme leader gained the upper hand against Tomura and tried to tear his finger off one by one. At that point, Tomura's Quirk underwent an Awakening, allowing him to disintegrate things without need all five fingers. The supreme leader immediately dropped him for fear of being crumbled to dust.
Tomura began to remember his repressed childhood memories and was able to achieve a greater level of power because of it. Tomura was able to spread his destructive effect across the entire city. The supreme leader, even with support equipment to increase the strength of his Quirk, was unable to combat the Awakened Tomura. The supreme leader would have died had he not amputated his own legs.
In the aftermath of the fight, Trumpet and his soldiers raced over to rescue their leader, but the supreme leader ordered them to stand down, acknowledging that the Army had lost. Gigantomachia had seen the whole thing and began to accept Tomura as the successor of All For One.
The League agreed to spare the Army, but in exchange, the Army must become subservient to the League. The supreme leader agreed; and so the League of Villains and the Meta Liberation Army merged and became the Paranormal Liberation Front.
The League of Villains was the most powerful villain organization in the criminal underworld. It was organized by All For One, a man who ruled the Japanese criminal empire for decades and prepared the League specifically for Tomura.
Initially, the League of Villains ranks were made up of a large number of weak villains and a single Nomu that could challenge All Might. Their bold attack on the U.S.J. ultimately failed and their numbers dwindled down to just Tomura and Kurogiri. After Stain inspires a new wave of villains to join the alliance, the League of Villains becomes a much more formidable organization.
Tomura gains strong new allies and forms the Vanguard Action Squad with Dabi as its leader. They are able to take on a team of Pro Heroes and U.A. Students while accomplishing their mission to capture Katsuki. However, this comes at the cost of A-Rank villains Muscular and Moonfish.
The League of Villains takes an even larger hit once All For One gets arrested, but they slowly rebuild their strength. Gigantomachia's recruitment and the development of new, more powerful Nomu like High-End have boosted the alliance's ranks. They possess destructive fighters like Tomura and Dabi as well as espionage specialists like Himiko and Twice. Giran's support and Mr. Compresses brains are also essential to the organization. The League took a blow with the death of big sis Magne and the incarceration of Kurogiri.
The League of Villains have proven to be the greatest threat to Hero Society as the world knows it. They are responsible for All Might's retirement and several assaults on U.A. High School, the pillars of Hero Society. The League of Villains appears to be the group primed to capitalize on the fall of the Symbol of Peace and rise up as the new rulers of society.