"A Duel Within", known as "Glimpse of the Supreme King" in the Japanese version, is the one hundred and twenty-ninth episode of the Yu-Gi-Oh! ARC-V anime. It aired in Japan on October 30, 2016 and in Canada on February 9, 2018. Nicktoons aired on August 4, 2018. It became available with official subtitles via Crunchyroll on November 28, 2017.
Yuya battles against Z-ARC, who is trying to consume him. Meanwhile, Declan boldly confronts Leo in order to stop his ambition. As the two’s respective battles rage on, Yugo and Yuri confront each other in another place. When the four dragons are summoned to their respective Fields, they begin to resonate, as if heralding the Devil’s revival.
Featured Duel: Yuya Sakaki and Declan Akaba vs. Leo Akaba
Turn 5: Declan
Declan Tributes "Alexander" and "Caesar" to Tribute Summon "D/D/D Doom King Armageddon" (3000/1000). The effect of "Caesar" activates as it was sent to the Graveyard, allowing Declan to add 1 "Dark Contract" card from his Deck to his hand. He adds "Deceitful Dark Contract with the War Deity" and subsequently activates it. Declan activates the first effect of "Illegal Dark Contract with the War Deity", targeting a monster he controls and one his opponent controls. He targets "Armageddon" and Leo's "Spirit Tech Force - Pendulum Governor". During the Battle Phase, the ATK of his monster will increase by 1000 and the ATK of his opponent's monster will decreased by 1000. "Armageddon" attacks "Pendulum Governor" (as "Armageddon" is a Level 8Pendulum Monster, it is not prevented from attacking by the effects of "Pendulum Governor"), but Leo activates his Set "Dis-Swing Fusion", negating the attack since a Pendulum Monster is attacking and then taking control of the attacking monster, preventing it from being destroyed by card effects. The second effect of "Dis-Swing Fusion" allows Leo to ignore one of the Fusion Materials of a Fusion Monster and use monsters in his hand or on his field as the remaining Fusion Materials to Fusion Summon that Fusion Monster. Leo fuses "Pendulum Governor" to Fusion Summon "Master Spirit Tech Force - Pendulum Ruler" (3500/3000). As a monster was Special Summoned, Yuya activates his Set "Twin Big Shields", preventing 1 monster he controls from being destroyed by battle or card effects twice per turn. He targets "Gatlinghoul".
Turn 6: Leo
Leo Pendulum Summons "Spirit Gem - Silpheed Core" from his hand (0/0) and "Spirit Gem - Salamander Core" from his Extra Deck. As "Salamander Core" was Pendulum Summoned from the Extra Deck, Leo can activate its effect to return it to the hand, and he does so. Leo activates the effect of "Pendulum Ruler", letting him Tribute a "Spirit Gem" monster that was Pendulum Summoned from the hand this turn that has not activated its effect to allow "Pendulum Ruler" to use that card's effect up to twice this turn and double any effect damage inflicted by this effect. He Tributes "Silpheed Core". He activates the effect now, letting him destroy a Spell/Trap Card on the field and inflict damage 800 to its controller. He destroys "Twin Big Shields" (Yuya: 3200 → 1600) and "Deceitful Dark Contract with the War Deity" (Declan: 3200 → 1600). "Pendulum Ruler" attacks and destroys "Gatlinghoul". (Yuya: 1600 → 1000) "Armageddon" attacks directly, but Yuya finds and activates the Action Card "Evasion", negating the attack.
Yuya activates the effect of "Raging Dragon", detaching all of its Overlay Units to negate the effects of as many face-up Spell/Trap Cards as possible and then destroying all other cards on the field, with "Raging Dragon" gaining 200 ATK for each destroyed card. He destroys both "Spirit Reactors", "Stargazer Magician", "Timegazer Magician", "D/D Cerberus", "D/D Savant Copernicus" and "Dark Contract with Exclusivity". The effect of "Pendulum Ruler" prevents itself from being destroyed. As he destroyed 7 cards, "Raging Dragon" gains 1400 ATK ("Raging Dragon": 3000 → 4400) "Raging Dragon" attacks and destroys "Armageddon". As Leo would take battle damage involving "Armageddon", it will be inflicted to Declan as per as the effect of "Dis-Swing Fusion" (Declan: 1600 → 200). "Raging Dragon" attacks and destroys "Pendulum Ruler" (Leo: 1600 → 700) Yuya activates the effect of "Performapal Nightmare Knight", banishing it from his Graveyard to inflict 1000 damage to all players who took battle damage this turn.
At this point, Yusho enters the Duel and takes the intrusion penalty (Yusho: 4000 → 2000 LP). By sending all cards in his hand to the Graveyard, Yusho activates "Restraining Sword of Impact" and ends the Battle Phase.
Since "Restraining Sword of Impact" was an illegal card, the Duel gets canceled.
The following cards appeared in this episode. Cards in italics debuted here.