Flashfire Fist

Flashfire Fist is a Ultimate Move used by Endeavor and his sons, Shoto and Dabi, using the Hellflame, Half-Cold Half-Hot, and Blueflame Quirks respectively.

Description
Flashfire Fist is Endeavor's signature technique. Endeavor raises his fire's temperature to its highest level and maximizes his power. Doing so, the Flame Hero can unleash devastating flame attacks or increase his speed dramatically. Flashfire Fist condenses Endeavor's flames into a white-hot point and is meant to act as a one-hit finisher. Endeavor can perform several variations of his Flashfire Fist move, each with a different form of attack.

Endeavor used Flashfire Fist several times against the High-End Hood, which raised his temperature dramatically, a glaring weakness when using this technique.

During Mission: Humarise, Shoto first used his father's signature technique, using it to perform his Ultimate Move, Jet Kindling, against Leviathan. He later used the same move against Dabi, during the Paranormal Liberation War Arc. Dabi revealed he's learned the technique as well, soon after.

Later development and mastery of his Quirk has allowed Shoto to form his own unique form of Flashfire Fist by merging his ice and fire into one ability. This form of Flashfire Fist uses "cold fire" to primarily prevent himself from getting burnt by, and gain an advantage over, other fire-based Quirks. This form of the technique requires a certain amount of concentration, otherwise it can falter.