Shigaraki Tomura's Decay is one of the most powerful Quirk abilities in the world of My Hero Academia. With its destructive powers, Shigaraki gains the ability to decay anything that he touches with his hand at an extremely high speed.
After awakening his Quirk, the rate at which Shigaraki's decay spreads has gotten faster than ever before, making him especially hard to take on in a fight. Furthermore, the Decay can also spread to things that are indirectly in contact with Shigaraki's hand. With such destructive capabilities, Decay is easily one of the most powerful Quirk in the series that only a few others can better.
10 Can Match: One For All
Known to be the strongest of all Quirks in My Hero Academia, One For All is currently wielded by Izuku Midoriya and was formerly in the possession of All Might.
This Quirk allows the user to stockpile energy and increases their physical attributes to sky-high levels. At maximum power, One For All is, undoubtedly, capable of matching Decay.
9 Can't Match: Gecko
The Quirk of Spinner of the Paranormal Liberation Front, Gecko grants him the appearance of a Gecko as well as the ability to stick to walls. That's all that this Quirk does and when compared to Decay, it doesn't really stand a chance.
In the future, this Quirk might get better, however, it still won't be comparable to Decay in any way.
8 Can Match: All For One
All For One is the former Quirk of the Symbol of Evil, All For One, and is currently wielded by Shigaraki Tomura. This Quirk allows him to steal the Quirk abilities of other people, and then either pile them up for usage or distribute them among other people.
It goes without saying that Quirk is among the strongest in the series to date and one that's possibly stronger than even Decay.
7 Can't Match: Dabi's Quirk
Dabi's Quirk, thought to be named Cremation, is a powerful ability that allows him to produce blue flames from his body and use them in his attacks. Although these flames are powerful enough to burn through his targets, they damage his own body as well.
Dabi's Quirk, while strong, doesn't compare to the ability of Decay, which can turn people to dust with indirect contact as well.
6 Can Match: Hellflame
The Quirk of Endeavor, Hellflame is an extremely powerful Quirk that lets him produce extremely high-temperature flames from his body. Like with Dabi's Quirk, there is a downside to using this Quirk for too long, however, its firepower appears to be vastly superior to Cremation.
When used against Hood, it was strong enough to overpower its regeneration factor as well, which just goes to show that this Quirk isn't one to be underestimated.
5 Can't Match: Fierce Wings
Fierce Wings is the Quirk of the Current Number 2 Hero, Hawks. This ability gives him two massive wings, granting him the power to fly, along with the skill of controlling each and every feather of his wings individually with great precision.
Fierce Wings is unbelievably powerful when used against most enemies, however, Shigaraki and his Decay is a cut above the rest, meaning it doesn't stand much of a chance.
4 Can Match: Permeation
Formerly wielded by Mirio Togata, Permeation is a Quirk that granted him the power to be able to phase through things. Although this Quirk isn't all that powerful and has more downsides than it has benefits, once mastered, it becomes one of the strongest Quirk abilities in the series.
With the power to phase through things and counterattack, Permeation would be the perfect counter for a Quirk like Decay.
3 Can't Match: Transform
Transform is the Quirk of Himiko Toga, one of the Lieutenants of the Paranormal Liberation Front. This Quirk gives her the power to change her appearance into that of anyone whose blood she ingests.
Furthermore, after awakening her Quirk, Toga has also gained the power to use the Quirk of those whose blood she ingests. Although overpowered, the requirements for using its powers are still a massive disadvantage, making it weaker than Decay.
2 Can Match: Half-Cold Half-Hot
Half-Cold Half-Hot is the Quirk of Shoto Todoroki, the son of Endeavor. This Quirk grants him the power to control high-temperature flames from one side of his body and ice from the other side.
According to Endeavor, using this Quirk, Shoto can even surpass All Might, the strongest Hero of all time. Without a doubt, this Quirk is worthy of being compared to Decay.
1 Can't Match: Double
Double was the Quirk ability of Jin Bubaigawara, also known as Twice. As a Lieutenant of the Paranormal Liberation Front, Jin was quite a capable fighter and much of that was down to his Quirk.
Double granted him the power to split himself into two and after awakening his powers, he could infinitely clone himself. His Quirk is said to hold the power to match a nation's might, however, it still pales in comparison to Shigaraki's Decay.