MHA quirk ideas

One for all

Description: One For All is a transferable Quirk that can be passed on from one user to the next. Its name comes from its nature; being 'one' Quirk for 'all' people. In order for the Quirk to be transferred, the recipient must ingest a sample of the predecessor's DNA (ex. a strand of hair or a drop of blood).

The origin of One For All is itself a powerful will that refused to submit to All For One. For this reason, One For All cannot be stolen by any means. In order for the Quirk to be transferred, the current owner must freely choose to transfer it. However, it can be forcibly given, as the recipient doesn't have to agree to anything. Since One For All can't be forcibly taken, it is the only Quirk that can be used in combat against All For One, as any user of All For One would simply be able to steal any other Quirk. One For All also allows the user to stockpile an enormous amount of raw power, allowing them to significantly enhance all of their physical abilities to a superhuman level. This results in unbelievable levels of strength, speed, agility, and durability.
The user can focus the stockpiled power into a single body part, or spread the power evenly throughout their body, although, focusing the power puts a greater strain on the part of the body where the power is focused. The user is also able to control the percentage of the power that they activate. One For All can even grant the user an exceptional strength boost to their given Quirk if they have one. The core of One For All has grown in strength from being passed from user to user, and the Quirk Factors of all of the previous users have merged into the core. The current user, Izuku Midoriya, has the exclusive ability to access the Quirks of previous One For All users. The Quirks have significantly increased in strength since they were used by their original users; this is due to the nature of One For All's core stockpiling power and increasing in strength from user to user. In addition to the Quirk Factors merging with the core, One For All carries echoes of the consciousnesses of all of the previous users. One For All has some kind of subconscious realm where the previous users can manifest. It is later revealed that this is due to the fact that Quirks are engraved with the consciousnesses of their users, so any new user who receives One For All has their consciousness embedded into the subconscious realm. It was originally believed that the consciousnesses can only be embedded into One For All if the user possesses a Quirk, however Toshinori proved this to be false: since he didn't have a Quirk or a Quirk Factor to have his consciousness copied into, Toshinori instead was able to actually imbue a true piece of his consciousness inside of One For All. This allows the fragment of consciousness to fully interact with the other users and share with them everything the real Toshinori knows, which is how the other vestiges were able to learn about the life shortening side-effect of One For All. The subconscious realm within One For All was originally a barren landscape surrounded by darkness, and vestiges of the previous holders could only share brief visions with one another. However, after Tomura and All For One attempted to steal One For All, they drew the vestiges out by sheer force, stabilizing the vestiges within and allowing the current and previous users of One For All to communicate with each other freely. The realm took the form of the ruins of a conference room with chairs, one for each holder, though the second and third users initially choose not to sit and stand in the corner with their backs turned. After having been stabilized, the previous users can now fully interact with Izuku whenever they wish, giving him advice on their Quirks and how to best use them. The realm also seems to have some connection to One For All's counterpart Quirk, All For One. The One For All realm appears to be the room where Yoichi first met his eventual successors, the second and third users of One For All, the very room where the stockpiling Quirk was forced on him and fused to Yoichi's transference Quirk to create One For All itself. All For One's failed attempt to steal One For All from Izuku removed all communication barriers between him and his predecessors. Now Izuku can freely manifest the spirits of past One For All users while remaining conscious.
One For All draws power from the cries of help of those in need, as they are like a direct order to the user.

One For All also seems to alter the user's appearance in different ways. For All Might, it significantly enlarges his muscles and overall body mass to make him look like a completely different person, similar to a giant. For Izuku, usage of One For All causes the empowered part of his body to glow, with vein-like lines crossing through each other. His body also generates crackling, green energy that resembles lightning bolts when he activates One For All: Full Cowl. It is unknown what the usage appearance of One For All looked like for its previous handlers, however.

One For All itself can be duplicated, but since it is an accumulation-type Quirk, the power stored inside cannot be duplicated as shown when Neito Monoma did not gain any substantial increase in power after copying it.

Flaws: When One For All is transferred, the new user's body is not naturally suited to it as they would be with a Quirk they were born with (ex. Someone who breathes fire doesn't burn their mouth while using their ability). In addition, One For All is a lot to handle; if one's body can't handle the power, then their body could be blown apart. Because of this, the successor must undergo intense and rigorous physical training. After One For All is transferred, the previous user is left with only residual power from the Quirk (or "leftover embers"). While they would still be able to utilize the power to essentially the same degree as before, continuous usage of it will cause their power output to decrease, until the wielder is not able to make tangible use of the Quirk at all. After All Might's final battle against All For One, his ability to sustain his Muscular Form was reduced to seconds, rending him unable to make any use of his residual power.

Following the research conducted by All Might, as well as the discourse of the One For All vestiges, it is revealed that One For All can affect the user's lifespan. If a person who already has a Quirk receives One For All, the extra Quirk places an enormous burden on their body, depleting the user's life force and shortening their lifespan. It is analogous to adding water to an already-full cup, causing it to overflow and breakdown. The rate at which the person's life decays is unknown, but Hikage, the fourth user, received One For All at the age of twenty-two and died of "old age" eighteen years later, at the age of forty. This weakness can be circumvented if an inheritor does not already have a Quirk, since the Quirkless user would be an "empty cup" that is filled by One For All.

While One For All cannot be stolen by any means, the users do admit that, theoretically, it is possible for All For One to steal One For All, provided he is able to overwhelm the collective will of all its users. Yoichi speculates that as the reason All For One raised Tomura Shigaraki to have overwhelming rage. When manifesting themselves in the unconscious realm of One For All, the current user's body is not all there at first. Some parts, such as their mouth, take time to learn how to fully manifest, making it more difficult to communicate with the other vestiges. This weakness was inadvertently removed by All For One when he unsuccessfully attempted to steal One For All from Izuku. Consequently, there are no communication impediments between all One For All users.

Name of Superpower:
Unknown Quirk: An unknown Quirk that originally belonged to the second user of One For All.

Fa Jin: The Quirk wielded by the third user. This Quirk allows the user to build up and store kinetic energy as they move, this energy can then be released as an explosive burst of speed and power.

Danger Sense: The Quirk wielded by the fourth user, Hikage Shinomori. This Quirk allows the user to detect nearby threats.

Blackwhip: The Quirk wielded by the fifth user, Daigoro Banjo. This Quirk allows the user to produce tendrils of dark energy which are useful for long-range grappling and increasing the user's mobility.

Smokescreen: The Quirk wielded by the sixth user, En. This Quirk allows the user to generate thick clouds of smoke from their body, which can obscure people's vision.

Float: The Quirk wielded by the seventh user, Nana Shimura. This Quirk allows the user to levitate.

Quirk type: emitter/ assimileted quirk (The Quirk factors of each of the previous users have merged with the core of One For All and have since increased in strength due to One For All's nature of stockpiling power. Izuku is the first user capable of accessing the Quirks of the previous users. Because All For One would constantly hunt and steal the most powerful Quirks, most of the user's Quirks are rather unexceptional by themselves and do not have enough potential to be raised to ultimate move level)

Quirk range: Melee and long-range