Blueflame

Blueflame was the Quirk carried by Dabi, an Emitter power tuned for long-range destruction. It runs on the same principle as Hellflame, the ability belonging to his father Enji Todoroki, letting its owner call fire out of his own body. The difference is color and consequence: what Dabi produced arrived blue, a visible signal of temperatures well past normal combustion.

The power showed up early, in Chapter 74, but waited until Chapter 230 to be given a name. Its animated appearances follow the same split, first in Episode 41 and named in Episode 110. Because the fire was orange and red in Toya's childhood and only shifted to blue at puberty, Blueflame appears to be a later label for a Quirk once known by something else.

Ignition asked almost nothing of Dabi. Blue fire could surface anywhere along his frame in a heartbeat, and whatever his skin touched tended to catch at once, tough mineral and living tissue alike. One tree inside The Beast's Forest gave him starting point enough to set most of the woods burning and pen everyone there inside a ring of flame.

Measured output sat at 2,000°C or higher, above lava and above conventional fire, which is exactly what the blue tint announces. Clusters of villains were reduced to ash within seconds, and Endeavor, enormously heat-resistant thanks to his own flame Quirk, could still be scorched through. Brightness counted too, making the fire a workable answer to a power such as Dark Shadow. Emotion set the dial: the angrier Dabi grew, the hotter the flames climbed.

The cost was structural. Toya took after Rei Todoroki physically, meaning a constitution geared toward surviving cold, so his body could never safely hold what his Quirk made. Sustained use left his skin puffing, hissing, and charring away, which gutted his stamina and ruled out drawn-out fights. Long stretches stripped his sense of touch until he risked going wholly numb, and any slip in emotional control drove the fire past what his flesh could take. By the Final War his burned tissue was crisping and falling off, and he admitted his body would give out at that pace. Right at the edge of death the Quirk did something unprecedented, producing his mother's Frost and briefly resembling Shoto's Half-Cold Half-Hot, framed as separate from an Awakening.

Toya Todoroki, later the villain Dabi, is the only person shown with this Quirk. He came out of a Quirk Marriage arranged between Enji and Rei, and the fire he inherited outstripped his father's. Enji saw promise and started training the boy, then shut it down once it became clear Toya's frame followed his mother's and could not tolerate its own output.

Toya refused to stop, working at Sekoto Peak in secret and scorching himself over and over, and there he found the link between his temper and his temperature. When Enji declined to come see how far he had come, the boy broke down and his own fire nearly finished him; he had been taught how to raise the heat and nothing about putting it out. Surviving became a purpose. As Dabi he memorized every technique his father owned, and with pain no longer registering, his old limits were gone.

He fought mostly at range with waves and flamethrower streams, kept short bursts for close work, fenced targets behind walls of fire, and flew on jets from his soles. The Quirk paired lethally with Compress, since anyone compressed alongside his fire simply burned. Because output ate at him, he rattled opponents to buy cooldown and learned to bank reserves by pulling heat off an attack. His arsenal was borrowed entirely from Endeavor or Shoto: Flashfire Fist, Jet Burn, Prominence Burn, Hell Spider, Hell Minefield, Vanishing Fist, and Phosphor. After unmasking during the Paranormal Liberation War he burned through Best Jeanist's carbon fibers, overpowered Nejire Hado, and beat his youngest brother. In the Final War he set Kamino ablaze, having banked heat internally since escaping Shoto's ice, aiming to detonate and cremate everything within five kilometers. The blast was smothered by the combined ice of Rei, Fuyumi, and Natsuo plus a strengthened Great Glacial Aegir.