Hell Flame gives Endeavor flame manipulation abilities.
He can create and control fire at will, as well as shape the flames as he sees fit. He also has the ability to control the fire's temperature, and can heat it up to the point where it even turns blue. Although he is almost always seen covered in flames, Hell Flame is activation-based and can be deactivated.
Nearly all of the moves used with this Quirk were seen in the anime.
Blue Flame: Endeavor is capable of heating up his fire to the point it changes colour to blue. This fire is significantly stronger than his regular flames, and is capable of burning flesh to carbon at the cellular level. This ability is so powerful, it can easily defeat a healing-type Quirk.
Fireball: By collecting fire in his hands, Endeavor can create a small fireball about the size of a baseball, and throw it as his targets. It does require him to have precise aim, however. The fireball also appears to have mass, but will stay together when thrown.
Wall Run: By heating up the soles of his feat with his Quirk, Endeavor is able to run along walls by creating melted points in the surface he wishes to run across. He has to move quickly however, since he is still affected by gravity.
Flame Spear: Endeavor generates a spear made of of fire from his Quirk, which has solidity. He can then use it like a regular spear, and throw it at his targets to create a deadly attack.