King Onyx alongside a Vulcan subject
Titles The Fire King,
Immature Fool,
He who shall cover the earth in flames
Relatives Vulcans (sisters)
Affiliations Gwendolyn (love interest),
Oswald (temporary servant)
Gender Male
Race Vulcan
Homeland Volkenon Lava Pits
Profession King
Bringer of Armageddon
Abilities/Powers Pyrokinesis,
Great strength,
Capable of transforming into a powerful behemoth
Weapon None
Voice Actor Nolan North (uncredited)
Seiyū Tomokazu Seki

Inferno King Onyx is the immortal ruler of the Vulcan race and presides over the Volkenon Lava Pits. He is also one of the five disasters of Armageddon.


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Onyx in his true form fighting Oswald

Onyx, in his human form, is a handsome muscular man, with bronzed skin, pointed ears, and up-swept opalescent white hair, wearing dark red armor leggings and a matching scarlet skirt-cape, as well as gauntlets. He is otherwise bare-chested and wears a golden crown crested with a large black onyx, in addition to a collar that matches his armor. This guise is, in fact, a ruse: like the rest of his people, his true figure is that of a fiery monster, in his case a hulking, demonic creature formed from magma. He allows Gwendolyn to leave the lava pits unharmed during her own story, as he believed she would be frightened by his true form and did in fact want to marry her.


Initially Onyx seems little worse than just arrogant and used to getting what he wants, and mostly behaves himself during Gwendolyn's story. Beyond that, more and more of his negative traits begin to show, revealing him to be destructive, cruel and greedy. His love for Gwendolyn can been seen as both twisted and misunderstood. While forcefully demanding of her love, and him once saying that he would rather keep her forever asleep so she may be with him (a fate which would be cruel to Gwendolyn, and incredibly unfair), there are hints that there is something more to his feelings.

His obsession with her purity could be a reflection of how he views himself. Gwendolyn has undoubtedly killed many but her unique demeanor shows to others that she is much more than a mere murderer, while if he, a monsterous being of flame and magma, were to have even minor negative traits, he would always appear as an evil creature of death and destruction, nothing more. He envies Gwendolyn for the fact that she remains for the most part unscathed as a Valkyrie. Onyx perhaps needs to come to terms with himself and his identity.

Oswald, who bears a similar disposition to the Inferno King, infuriates Onyx to no end and he is jealous that despite their similarities and the fact that Oswald may perhaps be considered even more monstrous than he, that the Shadow Knight wins Gwendolyn regardless, and Onyx's own fervent need to have her is the conflict of him believing she could never love him, and his own inability to voice how much he really cares. While he is fully capable of being cruel, evn merciless, it seems that his actions are driven from a conflicted character.


Battle with the Shadow KnightEdit

Onyx becomes involved in the story when the sleeping Gwendolyn is given to him by Skuldi of the Three Wise Men, hoping to start a war between Volkenon and Ragnanival. Demon Lord Odin travels to Volkenon to reclaim his daughter, and after learning from Onyx that his plans were to marry Gwendolyn to improve his image and to get the girl he wanted, Odin reveals that Gwendolyn would not be forced to love the man who awakened her and leaves Volkenon.

Oswald arrives shortly afterward, hoping to reclaim Gwendolyn himself before she was awakened by Onyx and forced to love him against her will. He finds and notices in relief she was still asleep, but Onyx arrived shortly afterward. The two do battle, with Oswald the victor. Onyx then revealed the extent of his love for Gwendolyn, and Oswald in pity, offers his services to the Inferno King for one time only.


Oswald didn't have to wait long, for shortly after he woke Gwendolyn Onyx called him to destroy a dragon that had been threatening the Fire Nation recently. In fact he suspected it was the Last Dragon Leventhan and hoped the dragon would kill Oswald. When Gwendolyn arrived to find him, he said he would assist Oswald if she agreed to marry him. When Gwendolyn refused and went to save Oswald herself, Onyx sent his Vulcans after her, ordering them to capture her alive.

After Gwendolyn defeated the baby dragon, Onyx arrived and began to taunt Oswald. Gwendolyn threatened to kill Onyx if he continued, amusing the King to the point of him allowing Gwendolyn to leave in peace.

Armageddon Edit

After the Armageddon began, Volkenon began to sink into the sea, forcing Onyx to invade the mainland to ensure his people's survival. He chose first to invade Ringford in order to prove the prophecies false: Since there was no known World Tree, he believed he was unstoppable.

His armies managed to destroy the Vanir and burn down most of Ringford. The Fairy Queen Mercedes herself came to stop him, and the two did battle, both receiving mortal wounds during the battle. As he took his last breaths, Onyx demanded to know how he could be dying, claiming it wasn't in the prophecies. He overhears Mercedes, herself dying as well, returning her true name to the heavens: Yggdrasil, the name of the World Tree in Norse Mythology. As Onyx crumbled into ashes, dying in the normal fashion of his kind, he still believes the prophecies are incorrect, as no one is capable of surviving the now-barren lands.

False EndsEdit

If Cornelius or Velvet battle Onyx, there will first be a scene of his army destroy the Vanir, and then the battle will begin. Either of the two will only be able to wound Onyx, enraging the Vulcans, causing them to attack the character in a mass, overwhelming them and reducing them beyond even ashes. Onyx then urges his army onward, his path now set on the Crystallization Cauldron.

If Gwendolyn battles Onyx, the two get into an argument upon her arrival, Gwendolyn urging Onyx to stop and Onyx lashing out at her for choosing Oswald over him. In a rage, Onyx assumes his true form and kills the Valkyrie princess. Upon realizing what he did, Onyx held Gwendolyn's corpse close, cursing the fact that every treasure he holds invariably turns to ashes. He orders his Vulcans to leave him, and waits for death while holding Gwendolyn, promising to never let her go.

If Oswald battles Onyx, Onyx claims their fight this time will be different than their previous one, for Onyx absorbed the hottest magma of Volkenon into himself. He proves his claim correct, for Oswald was unable to best Onyx. In desperation, Oswald again called upon his shadow powers despite using them extensively during the battle, and finally succumbed to the Belderiver's curse, becoming a Desecrator. Onyx ordered his forces to allow Oswald to continue wandering the dying Erion and said he would inform Gwendolyn of Oswald's fate when he found her. Oswald roamed Erion, uttering Gwendolyn's name one last time.

Boss Edit

Onyx is a boss that needs to be treated with care, due to his arsenal of attacks being capable of inflicting large amounts of damage along with inflicting Burn. He like Onyx is most of the time slow and predictable although a handful of his attacks are swift and difficult to overcome so the player needs to be on alert.

His attacks involve sprouting tentacles of fire from his chest which is easily avoided by blocking or stepping away, he usually signals this by extending his hands. While performing the same pose he is capable of erupting fireballs into the ground which then rise into arcs of fire that finally cool down leaving rocky formations. It is imperative that one is not trapped in one of these arcs, since while they can be destroyed, they are tough to break and can fatal in conjunction with Onyx's most powerful attack, a full body tackle. Due to Oswald and Mercedes being unable to guard in the original game, this attack can kill them quick, even more so considering that Onyx also performs jumps if his target is airborne. To avoid this attack the player is recommended to jump behind Onyx before he attempts to run forward or simply run as far away as possible. Since this attack is symbolized by Onyx glowing on very bright colours and takes time to charge himself before running. Worthy of note however is that Onyx repeats this three times.

Other attacks that Onyx performs involve using propelling his fists as rockets, which swing for a long time and their trajectory is nearly unpredictable. However they can attacked so they return to Onyx sto they stop harassing the player. Onyx can also perform a series of consecutive punches. Therefore it is recommended to keep a certain distance from Onyx or get behind him as often as possible. It is nonetheless recommended to use the Overload skill and Painkiller potion.

In Leifthrasir Onyx's difficulty has been at large reduced. While his attacks remain strong and can induce Burn with nearly any attack now, since all characters can Guard now, this reduced the threat of Onyx's most powerful attacks. The availability of skills and Oswald's Berserk Mode being governed by another gauge other than POW, also helps making the battle easier.


  • Onyx is the only disaster with a generic boss theme, being "A Hard Fight and then Hope", the boss theme for all Epilogue bosses in the normal books. The other ones all have unique boss themes.
  • Onyx can be easily beaten either time by releasing a Slime to completely restrict his movement and actions.
  • Onyx is likely based on Surtr, king of the fire giants in Norse mythology. During Ragnarok, the end of the world, the flames that Surtr brings forth engulf the entire world. Surtr's name also translates as "black", of which the word Onyx is a synonym.
    • Symbolically speaking however, Onyx and his kingdom may represent the "Ring of Fire" in Der Ring des Nibelungen. In the opera, the Valkyrie Brynhildr (on whom Gwendolyn is based on), defied Odin and was put to sleep, confined in a castle where she was set to marry a man (much like in the game). The castle was surrounded by a "Ring of Fire" whom only the hero Siegfried (on whom Oswald is based on) could traverse on to wake up the sleeping Brynhildr, upon which the two fall in love with each other.
  • Onyx is voiced in Japanese by popular voice actor Tomokazu Seki. His role as Onyx opposite Ayako Kawasumi as Gwendolyn almost exactly mirrors the similar roles of their respective characters from the anime Fate/stay night. In Fate, Seki played Gilgamesh, an arrogant and powerful king obsessed with possessing the beautiful and proud warrior maiden Saber, played by Kawasumi. He also voiced Stahn Alieron from Tales of Destiny, who is also an aggressive fire user.