Fire Dragon Slayer Magic is a type of Dragon Slayer Magic that grants the user various characteristics typical of a Fire Dragon: lungs capable of spewing flames, scales that grant protection against fire, and nails covered in flames. Consequently, Fire Dragon Slayer Magic allows the user to produce and control fire from any part of their body, which can be used both in melee and as a ranged form of offense. The generated flames can be manipulated in a wide variety of ways, their “type” can be changed at will, and they can even be given a material consistency. Such fire seems to have a “blunt” effect to it, seemingly causing bludgeoning damage alongside burning. Flames produced by this type of Magic provide much more heat than standard flames, and are said to burn as strong as the Flame-Flame Fruit. The user’s body temperature is capable of melting iron, burning off poison and stigmatas, and vaporize sand. The user's flame are directly connected to their feelings, meaning the more emotional they get, the warmer their flame will become; this effect is referred to as “Flames of Emotion”.
In addition, the user can consume external sources of fire to restore their body to a healthy state and regain their reserves of strength, something that also makes them immune to most types of fire, due to their capability of nullifying fire-based attacks by sucking them in and eating them; the consumed fire also seems to possess a different “taste” according to its “quality”. However, the user can’t eat their own flames, or things set on fire by them, to reinvigorate themselves. While classes of flames that are “higher” in rank to those produced by this type of Magic (like those employed by a Fire God Slayer) can’t be eaten directly and will therefore damage the user, momentarily self-nullifying all of the user’s Magic Power will grant them enough room to consume and even use such flames.
If a Fire Dragon Slayer is somehow capable of successfully eating lightning, they will enter Lightning Fire Dragon Mode. In this form, the lightning and flames will fuse and the user's attacks will possess the properties and destructive ability of both elements as well as enhance their own physical abilities.
Against Logia-type Devil Fruit users, a Fire Dragon Slayer is exceptionally strong enough to overpower many (namely Smoke, Gas and Sand) through the basic principles of opposing elements, but is weak against those producing magma, an element whose heat burns hotter than fire; it isn't strong enough to even melt the ice produced by the Chilly-Chilly Fruit, whose freezing energy is far stronger than standard Ice Magic.
- Fire Dragon's Roar: The user first inhales, gathering fire in their mouth, and then releases such fire in the direction of their opponent, creating a large, exploding fireball which damages and burns the opponent. This spell can be performed two ways: the first, and more "complicated" way involves the user putting their hands before their mouth, in a pose resembling that of a trumpeter, before releasing the fire, prompting it to be expelled between their fingers. The flames produced by this version start out as a very thin stream, enough to be fit between the user's fingers, before suddenly enlarging to strike the opponent. The other simpler, and seemingly faster way, simply has the user quickly gathers flames in their mouth and then releases them, with no seeming stance required, producing a much larger burst of fire.
- Fire Dragon's Iron Fist: The user engulfs their fist in flames and then punches their opponent, causing, aside from sheer blunt damage, damage from the flames as well. This attack can also be performed with both hands at once.
- Fire Dragon's Claw: The user ignites their feet with flames and proceeds to assault the opponent with a powerful fire-enhanced kick, with the flames greatly augmenting the power of said kick. They can also create flames from the feet, greatly enhancing speed and allowing the user to jet-propel in any direction they desire. This makes it easier for the user to get close to opponents that they wish to engage in close combat. The user can also combine the jet-propulsion capabilities of this spell for use with other techniques.
- Fire Dragon's Brilliant Flame: The user generates fire on both of their hands and then joins them, creating a unique, larger flame as a result. The user then throws the flame like a very large fireball at the enemy, blowing them away.
- Fire Dragon's Sword Horn: The user engulfs their entire body in flames and then propels themselves against the opponent at high speed, hitting them with a powerful headbutt. The user then proceeds to send the enemy flying up in the air with a pillar of fire produced from their body.
- Fire Dragon's Wing Attack: The user rushes forward against two opponents. While doing so, the user produces a large stream of fire from each of their arms, which, when it comes in contact with the foes, burns them and at the same time sends them flying away behind them due to the blunt force of the produced fire. Such flames take the rough form of a pair of Dragon's wings, thus the name of the attack. This spell can also by employed by first grabbing the targets' heads and then producing the fire to strike them, as shown when Natsu Dragneel used it for the first time.
- Fire Dragon's Flame Elbow: The user creates intense, bursting flames from their elbow, boosting the striking power of the corresponding bare punch, which they then use to strike the target, who is then sent flying (at least) several meters away from the user.
- Fire Dragon's Crushing Fang: The user ignites one of their hands and then swings it in an arc, striking the target with their fingertips, leaving a flurry of flames in their wake.
- Fire Dragon's Fire Fang: The user ignites their canines and bites down on their opponent, generating an explosion that burns the target while piercing their flesh with flame-empowered fangs.
- Fire Dragon's Mirror Wall: The user conjures up a large wall of fire to block and deflect enemy attacks.
- Fire Dragon's Roasting Bath: The user engulfs their entire body in flames to heat up the surrounding area. This is powerful enough to make water reach scalding temperatures.
- Crimson Lotus: Fire Dragon's Fist: The user ignites their fists with large, light spheres and then charges at the opponent, hitting them with a continuous barrage of punches enhanced with Fire Dragon Slayer Magic. Each punch produces a powerful explosion, with the resulting complete attack being strong enough to break through Gajeel Redfox's Iron Dragon's Scales, which are noted for their resilience, and defeat him, whilst simultaneously destroying Phantom Lord's headquarters.
- Crimson Lotus: Exploding Flame Blade: The user ignites their arms and generates long torrents of flames from them, which move to hit the enemy in a spiraling formation. Each connecting strike generates a powerful, burning explosion; an even larger explosion was shown ending the barrage when Natsu Dragneel used the attack against Gildarts Clive. This spell has been described as the ultimate Dragon Slayer technique. It was powerful enough to defeat a worn-out Laxus Dreyar, force Gildarts to take two steps back when attacked by it, and even more powerful than Sting Eucliffe and Rogue Cheney's Unison Raid: Holy Shadow Dragon's Flash Fang.