Explosion allows Katsuki to excrete sweat similar to nitroglycerin from his palms and ignite it at will to create various explosions.
The more the user sweats, the more powerful the explosions are. However, during cold weather, the nitroglycerin-like sweat requires slightly longer time to ignite, as opposed to heat, where conditions are optimal for ignition.
As the Quirk proved to be powerful and possibly fatal with the use of tools such as Grenadier Bracers, repeated ignition (especially with large explosions) will eventually result in wearing out the user's palm due to direct skin contact, causing pain to the user's arm and shoulder.
As mentioned by Katsuki Bakugo, the Grenadier Bracers serve to reduce the risk of overusing his Quirk as well as amplifying the effects of the explosions. However, triggering one of the bracers' firing pins creates a strong recoil that tolls the user's shoulder, although Katsuki seems to be completely unfazed by it due to his superior physical ability.
Additionally, creating explosions with both arms at the same time causes their overall strength to disperse between both limbs, leading to individually weaker blasts.
Katsuki is able to use Explosion to propel himself through mid-air, blind opponents and release long-ranged blasts, among other things. Explosion is a versatile Quirk, and coupled with his fighting talent and intelligence, Katsuki can come up with new moves with little difficulty. Due to Katsuki's battle ingenuity and natural aggressiveness, Explosion tends to be a very overwhelming Quirk for others to face against.
In battle, Katsuki favors all-out offense, using his Quirk's propulsive abilities to close the distance between him and his opponents, followed by a bombardment of close-range attacks that are often started with a powerful right swing. Despite having great mastery over his Quirk, Katsuki tends to recklessly cause unnecessary damage to his surroundings, which is a common issue in hero work as it may jeopardize missions that require more careful approaches.
Katsuki is very proud of his Quirk. Throughout his life, people frequently commended Explosion, leading Katsuki to develop a superiority complex. As a result, he became arrogant and condescending over others and their Quirks. Before getting into U.A. High School, Katsuki had the habit of using Explosion as a means of threatening and bullying Izuku, and while he has dropped that practice for the most part in the present, he still likes to use his Quirk as a way to intimidate foes during fights, usually by creating miniature explosions around both his palms.
Named Super Moves
- Blast Rush Turbo (爆速ターボ Bakusoku Tābo?): Katsuki throws his hands backwards and then causes an explosion in his palms, to propel himself forward. This move can also be used to achieve a pseudo form of flight, as Katsuki used this move to fly over the giant robots during the Obstacle Race during the Sports Festival.
- Stun Grenade (
閃光弾Sutan Gurenēdo?): Katsuki creates a sphere of light with his hands. The sphere of light implodes, causing an explosion around Katsuki, blinding anything in Katsuki's vicinity.
- Howitzer Impact (
榴弾砲着弾Hauzā Inpakuto?): Katsuki dashes into the air and creates two Explosions in his hands. While in the air, Katsuki spins himself around, building up momentum for his Explosions. After spinning himself around and gathering momentum for his Explosions, Katsuki fires an Explosive tornado at his opponent.
- AP Shot (
徹甲弾AP Shotto?): Katsuki stretches out one of his hands and uses his other hand to form a circle on the palm of his outstretched hand. Katsuki then fires an explosion through the circle, which creates a concentrated blast beam. By focusing his the path of his explosions into a single point instead of around his whole palm, Katsuki creates a concentrated blast with reduced area of impact, but with enough power to successfully pierce even solid concrete.
- Explosion - Wikipedia article about the phenomenon Katsuki can create with his Quirk.
- Nitroglycerin - Wikipedia article about the substance Katsuki produces from his hands.