Slayer Magic (滅法 (スレイヤーマジック) Metsu Mahō(Sureiyā Majikku) is a sub category of Lost Magic which has numerous forms. It strengthens the user's body to slay the creature that taught them the magic such as Dragon Slayer; where the dragon teaches the mage how to magically slay the dragon. While some forms of Slayer Magic like God Slayer and Dragon Slayer have an element taught to the mage such as fire, steel and air etc. Dragon Slayer magic can also be obtained by implanting Dragon Lacrima with a specific element into their body but this cannot be done with any other form of Slayer Magic. People who know this magic can also teach others a form of this magic shown when Hades taught the Flame God Slayer Magic to Zancrow.
Dragon Slayer Magic is a form of slayer magic which is (as the name suggests) taught by dragons and is used to slay dragons. The user can also utilize an element in battle such as fire, ice, steel and air etc.
Phoenix Slayer Magic is a form of Slayer Magic which is taught by phoenixes to slay their own kind. The user can utilize an element in battle. It is regarded as slightly weaker in terms of raw power to God Slayer; however, the user's wounds regenerate slowly over time, and the user does not need to consume an element to regain stamina, instead absorbing it the moment it is touched more than make up for this setback.
God Slayer Magic is a form of Slayer Magic which is taught by "gods" but can also be taught by another mage who knows this magic. It is used to slay "gods" like Dragon Slayer is used to slay dragons and it also has elemental styles.
Demon Slayer Magic is a form of Slayer Magic which is taught by demons to slay demons. In addition, Demon Slayer has elemental styles.
Devil Slayer Magic, otherwise known as the Devil Slayer Curse, is a form of Lost Magic that is gained through a pre-existing user of the magic or by reading a Book of Zeref. It allows the user to employ elemental magic that enables them to deal a very high level of damage to Etherious.
Spirit Slayer Magic is a form of Slayer Magic which is taught by spirits in order to slay them. The most notable of these is Celestial Spirits.