The XX-Burner (XX (ダブルイクス) BURNER(バーナー), Daburu Ikusu Bānā) is a vastly more powerful version of Tsuna's X-Burner. It can be used through his Vongola Gear-enhanced Cambio Forma and the new contacts and headphones prepared by Spanner. Tsuna is able to fire "Hard Sky Flames" from both hands, while "Soft Flames" are released from his Vongola Gear Cambio Forma's arm thrusters, firing twice the amount of power than the X-Burner. Once Tsuna releases this technique, highly powerful flames are released. Natsu seems to power these flames as well, as the front of the flames are shaped like him. These Flames are of such intensity and power that even large black holes disperse upon being hit. The XX-Burner can be fired in two ways. The first method is using the Sky Flame's Harmony characteristic. Usin