Half-Cold Half-Hot allows Shoto to generate ice from the right side of his body and flames from the left.
Half-Cold Half-Hot stems from the fusion of Shoto's father's Hellflame Quirk and his mother's ice Quirk through a Quirk marriage. As a result, Half-Cold Half-Hot is perfectly divided between the right and left sides of Shoto's body. This gives Shoto two powerful separate methods of combat that he may use regardless of the other to an extent, if he so chooses.
For the Quirk to function properly, Shoto needs to constantly alternate the use of both his sides, heating himself with his left side after using ice or cooling himself with his right side after using fire. Overusing either side might lead to either frostbites or overheating, with possibly fatal consequences.
Right-side: Using the limbs on the right side of his body, Shoto can drastically lower temperatures and freeze anything he touches.
Shoto is able to swiftly freeze entire buildings and streets, as well as create large waves of ice instantaneously. Despite its incredible raw power, Shoto possesses great control and direction over his right side. He can restrict the ice to avoid fatally freezing someone, or use precision attacks to freeze only certain portions of a target's body.
Shoto is capable of molding the ice into certain shapes to support himself. He consistently summoned barriers of ice to avoid being blown out of bounds during his battle with Izuku Midoriya. In that same fight, he created stairs of ice he could run up to elevate himself. During his battle with Katsuki Bakugo, Shoto generated a moving wave of ice that he surfed to recover from being thrown.
Prolonged usage of his right side will lower his body temperature to dangerous levels. When this occurs, Shoto's body gets covered in frost and his ice attacks lose their effectiveness. His maximum output brings him to his temperature limit almost immediately.
Left-side: From his left, Shoto can drastically increase temperatures and release scorching hot flames.
When Shoto ignites his flames, the resulting blaze covers his arm and the left side of his head. He is able to shoot out consuming streams of fire or protective short waves of it.
Due to Shoto's animosity towards his father, he held off on using his left side offensively for most of his life, activating it only for thawing victims of his freezing attacks. As a result, his manipulation of the flames is rather poor in comparison to the finesse of his right side. His lack of control has made adjusting to the high temperatures of his flames difficult for him. It is also possible for him to overuse his left side, causing his body to overheat to potential death, a weakness he shares with his father.
By chilling the air using his ice and then heating it in an instant using his fire, he can release a huge super-heated blast of flame that devastates anything on its path.
Fortunately, Shoto is capable of using his other side to counteract the dangerous effects of which ever one he happens to be overexerting. Activating both sides simultaneously is possible as well, but lack of practice has made this awkward for him, dulling his movements.
- Giant Ice Wall (大氷壁 Daihyōheki?): Shoto uses his freezing powers to generate a giant glacier-like wave of ice. He first used this move on Hanta Sero in the U.A. Sports Festival. It remained unnamed until the Final Exams, where Momo Yaoyorozu dubbed it. Shoto used a smaller variation of this move against Katsuki Bakugo.