Dragon Slayer Magic

Dragon Slayer Magic (滅竜魔法 Metsuryū Mahō) is a Caster-Type Lost Magic utilized by Dragon Slayers.

Description
Dragon Slayer Magic is a type of Lost Magic which allows its users to transform their physical bodies into a Dragon. As a result, the user can transform their body with features of their respective element, utilizing both offensive and defensive styles. They can consume external sources of their respective natural element to replenish their own energy. A Dragon Slayer is immune to the effects of their own element, and can consume external sources of their element to replenish their strength. However, a Dragon Slayer cannot consume the element that they produce themselves, and elements must be consumed through the mouth. It is known that certain Dragon Slayers have been able to consume elements other than their own, allowing them to combine both elements inside their bodies and use them to increase their abilities. Dragon Slayer Magic seems to be the only way to kill, or even hurt Dragons, who are shown to be mostly unaffected by other forms of Magic.

There are two ways one can learn Dragon Slayer Magic. Through the first way, one must be taught by an actual Dragon. The ones who learned their Dragon Slayer Magic through this method are referred as First Generation Dragon Slayers. Through the second way, one must have Dragon Lacrima implanted into their body. The ones who learned their Dragon Slayer Magic through this method are referred as Second Generation Dragon Slayers. There is also another way which is a combination of the above two methods: ones who both learned their Dragon Slayer Magic by receiving the teachings of a Dragon and also having Lacrima implanted into their body. The ones who learned how perform Dragon Slayer Magic by utilizing both methods are referred as Third Generation Dragon Slayers.

Dragon Force is the final, ultimate state that a Dragon Slayer can attain. When one enters Dragon Force, their skin becomes scaly like an actual Dragon's. The exception to this conceived notion are the Third Generation Dragon Slayers, who have scale-esque designs instead of having Dragon scales appear on their bodies. The exact conditions required for a First Generation Dragon Slayer to achieve Dragon Force are currently unknown. Natsu Dragneel, however, has achieved this state at least twice: once after eating Etherion-infused Lacrima, and again after consuming Jellal's Golden Flame of Rebuke. Second Generation Dragon Slayers seemingly enter Dragon Force when they make use of their respective Dragon Slayer Magic, though this is not always the case. Third Generation Dragon Slayers, however, can enter Dragon Force of their own free will.

History
This form of Magic was born over four hundred years ago during the Dragon Civil War. The Dragons split into two factions: those who supported peaceful coexistence with humans, and those who did not. However, the war ripped apart the lands and was locked in a constant stalemate. To end the stalemate, the Dragons that supported coexistence played a dangerous card: they taught their special Magic to the humans they sought to coexist with. Although the war shifted in their favor, the Dragons miscalculated; some of the humans that were taught this special Magic began to slay not only enemy Dragons, but allied ones as well. Such actions earned the humans who were taught Magic by the Dragons the name Dragon Slayer.

First Generation
Dragon Slayer Magic used by those who have been personally taught by a Dragon.

Second Generation
Dragon Slayer Magic used by those who solely had Dragon Lacrima implanted into their bodies.

Currently, we don't know if any of the Dragon Slayers are Second Generation

Third Generation
Dragon Slayer Magic used by those who have been taught by a Dragon and also had Dragon Lacrima implanted into their bodies.

Currently, we don't know if any of the Dragon Slayers are Third Generation