All For One's power to steal and redistribute Quirks makes it one of the most threatening My Hero Academia Quirks. When wielded by All Might's greatest enemy, All For One threatens Hero society itself. The Quirk's capabilities proved strong enough for the villain All For One to severely injure and nearly kill All Might. However, even the mightiest powers come with drawbacks to their benefits.
All For One is a complex and unique Quirk that is far from simple to wield. The unexpected consequences of acquiring great power turn All For One into as much of a curse as it is a gift.
WARNING: Minor manga spoilers in entry 9.
10 Humans Have Quirk Capacities
While Quirks continue to evolve in My Hero Academia's society, the average human body is capable of holding only one or two Quirks at once. A Quirk User risks damaging themselves if their power becomes too physically demanding to wield, such as the villain Dabi burning his skin with his fire Quirk.
All For One's users aren't immune to physical limitations despite having the rare ability to absorb and manifest multiple Quirks. As possessing greater power increases the strain on the body and the risk of injury, All for One threatens its users' health if it's allowed to accumulate too much power.
9 Great Power Doesn't Mean Invincibility
While All For One allows users to obtain more abilities than most people, All For One doesn't make users invincible. Despite the villain All For One's best efforts to overthrow Hero society with his Quirk, he was still defeated and incarcerated by All Might. Even if an All For One user attains immense power, the counterpart Quirk One For All exists to challenge them.
An All For One user can't always rely on their Quirk to win, and defeat remains a possibility in battle. Every Quirk has vulnerabilities that can be taken advantage of by clever opponents.
8 All For One Attracts A Lot Of Attention
The downside of having powerful Quirks is that people inevitably notice them. All For One leaves a big impact on people, as it dramatically alters lifestyles by removing or gifting Quirks. All For One victims who lose their Quirks are certain to remember who has stolen it, which leaves an All For One user with multiple revengeful enemies.
On the other hand, a person who receives a Quirk from All For One may turn on the user after gaining power. An All For One user lives with the threat of betrayal or victim retaliation. Remaining anonymous with the Quirk is next to impossible.
7 All For One Created Its Own Weakness
All For One is tremendously powerful, but the very Quirk that stands against it was created by All For One itself. When the villain All For One gave his brother a power-based Quirk, he unknowingly created One For All, which his brother gifted to future generations as a weapon against All For One.
Without All For One gifting his Quirk to someone who could pass Quirks on, All Might would never have inherited One For All and used it to halt All For One's reign. An All For One user wields a Quirk that has brought about its own downfall.
6 It Can't Be Used Without Hurting Someone Else
An All for One user may decide to use the Quirk for good. Unfortunately, doing so is extremely difficult, as All For One depends on stealing Quirks. All For One becomes a useless power if its user doesn't claim other Quirks for themself. The very act of using the Quirk harms others by taking away parts of their identities.
The only way to use All For One without hurting someone is by taking Quirks from people who freely offer them. Even then, there's no guarantee that the opportunity to do so will arise. An All For One user finds being heroic hard.
5 Current Users Are Affected By The Personalities Of Past Users
The current All For One user forms a mental link with the Quirk's previous user and can communicate with them through mental visions. Due to this link, the current All For One user is susceptible to being influenced by the previous user's personality. While this connection allows current users to learn from the previous wielder, not all personalities leave a positive influence behind.
If a past wielder of All For One possesses a cruel personality, current users will slowly acquire negative characteristics to some degree despite personal morals. All For One exposes its users to potentially bad influences that are difficult to avoid.
4 Every Quirk Has To Be Mastered
While an All For One user can steal almost any Quirk they want, each newly acquired Quirk requires training before the user can wield it effectively. Mastering a Quirk takes years depending on the Quirk's complexity, so stealing many Quirks demands dedication. An All For One user needs time to practice powerful Quirks to harness their full capabilities.
An All For One user will face difficulties battling experienced opponents if they fail to train their stolen Quirks effectively. The user depends on their ability to learn to become adept at using All For One.
3 All For One Requires Direct Touch
The All For One Quirk quickly steals and transfers Quirks, though it only works when the user physically touches the victim or recipient. If an All For One user faces an opponent who understands the Quirk's limitations, the intended victim will take care to distance themself for protection. Quirk users need to be immobilized long enough for an All For One user to activate their power.
Based on its limitations, All For One is a short-distance Quirk with a disadvantage against high mobility Quirk users. An All For One user must steal long-distance Quirks to assist with capturing opponents.
2 Not All Quirks Can Be Stolen By Regular Means
While All For One proves capable of stealing most Quirks, unique Quirks exist that All For One can only steal under specific conditions. All For One's counterpart Quirk One For All is only stealable by force if negative emotions override its will. An All For One user can't always get desired Quirks without going to considerable lengths to do so.
An All For One user needs to investigate unusually resistant Quirks to find ways to successfully acquire them. All For One as a Quirk provides no guarantee that efforts to obtain restricted Quirks will be worthwhile.
1 All For One's Abilities Weaken When The User Is Injured
All For One's strength depends on its user's physical condition and weakens when its user takes damage. When All For One sustained life-threatening injuries after losing to All Might, the All For One Quirk temporarily lost most of its power. An All For One user needs to recover from illness or injury to utilize their full potential.
Wielding All For One requires that users stay in top condition to steal, transfer, and harness multiple Quirks effectively. A wounded All For One user becomes increasingly vulnerable to attacks, just like any other Quirk wielder.