Kaiser Mariner

Kaiser "Kai" Mariner (カイザー・マリナー Kaizā Marinā), also known as The Blue Flame (青炎 Ao En), was an immensely powerful Fire Dragon Slayer as well as one of the original Dragon Slayers. He was the apprentice of the Blue Fire Dragon, Pyron, and the father of Troy Mariner.

Magic & Abilities
Fire Dragon Slayer Magic (炎の滅竜魔法 Honō no Metsuryū Mahō): As one of the original Dragon Slayers, Kai has complete mastery over his Dragon Slayer Magic. As with all Dragon Slayers, he can consume his respective element, with the exception of that which he has created, to replenish his energy reserves. Unlike Natsu's and Igneel's flames, the flames of Kai's Fire Dragon Slayer Magic is blue. The heat of his fire can increase in temperature, which is proportional to Kai's emotional state. He incorporates the flames he ignites into his fighting style, greatly increasing the damage of his blows. This fire is exceptionally strong - equivalent to a Dragon's fire - being able to burn even through metal. Kai's mastery over his Dragon Slayer Magic is so great that he is able to defeat multiple Dragon Slayers with absolute ease. Kai eventually lost all of his Magic after his fight against Acnologia.
 * Fire Dragon's Roar (火竜の咆哮 Karyū no Hōkō): Kai's signature Dragon's Roar in which he quickly gathers and releases a large quantity of blue flames from his mouth, capable of destroying everything in a large-scale area in front of him.
 * Fire Dragon's Talon (火竜の鉤爪 Karyū no Kagizume): Kai ignites his feet in blue flames, thereby increasing the power of his kicks.
 * Fire Dragon's Iron Fist (火竜の鉄拳 Karyū no Tekken): Kai engulfs his fists in blue flames and punches the target, causing, aside from sheer blunt damage, damage from the flames as well.