Muscle Augmentation is a Quirk that gives its user the ability to amplify, and to a degree, manipulate their muscles, granting a significant increase in strength, speed, and durability. When using this Quirk, muscle fibers can be enlarged to where they can no longer be contained by the user's skin. In addition, Muscle Augmentation gives the user the capacity to contend with One For All at 100%.
Muscular is the only wielder of this Quirk where it serves as his lone superpower. He uses Muscle Augmentation to cover his limbs with enhanced muscle fibers that protrude from his skin. He can freely choose which parts of his body his muscle mass covers in order to immensely increase his physical prowess. When fighting seriously, Muscular can obliterate a large portion of a cliffside with a single strike.
The augmented muscles also provide Muscular with heightened durability, as the fibers can act as a shield to absorb attacks. With enough protection, Muscular can even easily endure the force of Super Moves as powerful as Izuku Midoriya's 100% Detroit Smash, which is equivalent to the strength of All Might.
By magnifying the muscles in his legs, Muscular can move at blurring speeds that far outclass Full Cowl at 5%. Muscular's inflated speed also gives him the option to completely avoid incoming attacks. In order to counter Muscular's enhanced speed, Izuku purposely trapped his hand between the former's exposed muscle fibers so that Muscular couldn't avoid his next attack.
All For One gave Wolfram the ability to enlarge his muscles and greatly increase his strength. When activated, Wolfram's muscles don't protrude from his skin, instead, they glow bright red, altering his appearance as a result. This is similar to how One For All at 100% changes the appearance(s) of All Might and Izuku.
Combined with the Quirk Amplification Device, this Quirk gave Wolfram enough raw strength to momentarily overwhelm All Might and turn the tide of their battle. Using this ability, Wolfram was able to injure All Might and compensate for his weakness at close range when manipulating metal.
Hood mainly uses enhanced muscle fibers to support his other Quirks, giving him incredible destructive power. Hood can cover his arms and muscles, transform them into powerful tendrils, and increase their power even more by using it in tandem with another strength enhancement Quirk.
The brute force of this Quirk has shown to be levels above Muscular's own raw power, and allowed Hood to overwhelm Endeavor. Destroyed muscles can also be regenerated thanks to Hood's Super Regeneration.
- Aside from the transferable Quirk One For All, Muscle Augmentation is the second Quirk with the largest number of named users in the series, the first being Super Regeneration.