"A Most Brutal Duel", known as Reign of the Supreme King Dragon" in the Japanese version, is the one hundred and thirty-sixth episode of the Yu-Gi-Oh! ARC-V anime. It aired in Japan on December 25, 2016 in Australia on March 18, 2018. Nicktoons aired on September 22, 2018. It became available with official subtitles via Crunchyroll on January 16, 2018.
Right before Declan and others, who believe that Yuya's Dueling will bring peace to the world... Z-ARC is finally awakened. Z-ARC proclaims that the feelings of those who believe in Yuya have helped him revive. The Lancers' battle against Z-ARC, who uses his overwhelming power to bring despair to all, has just begun.
Featured Duel: Aster Phoenix and Sora Perse vs. Z-ARC
Turn 2: Aster
Aster activates "Polymerization", fusing "Destiny HERO - Drilldark" and "Destiny HERO - Decider" in his hand to Fusion Summon "Destiny HERO - Dystopia" (2800/2400) in Attack Position. Aster activates the effect "Dystopia" as it was Fusion Summoned to inflict damage to Z-ARC equal to the ATK of one of its Fusion Materials. Aster targets "Decider". The Pendulum Effect of "Zero" reduces any damage Z-ARC would take to 0, and the Pendulum effect of "Infinity" increases Z-ARC's LP by the same amount Z-ARC would've taken without "Zero" (4000 → 5600 LP). "Dystopia" attacks a "Darkwurm", but Z-ARC activates the effect of "Darkwurm", letting him negate an attack once per turn as he controls another "Supreme King" monster. Aster activates "D - Soul Burst", halving the ATK of a "Destiny HERO" monster he controls and inflicting the lost ATK as damage to all players. He targets "Dystopia" ("Dystopia" 2800 → 1400). The Pendulum Effects of "Zero" and "Infinity" reduce the damage Z-ARC takes to 0 and increase his LP by the same amount (Z-ARC 5600 → 7000) (Aster 4000 → 2600). As its ATK or DEF was changed, Aster activates the effect of "Dystopia", letting him destroy a card on the field. He destroys a "Darkwurm". Aster Sets a card.
Turn 3: Sora
Sora activates "Frightfur Sanctuary" by sending a card from his hand and two "Frightfur" monsters from his Extra Deck to the Graveyard. He sends "Edge Imp Frightfuloid" in his hand and "Frightfur Bear" and "Frightfur Tiger" in his Extra Deck to the Graveyard. While active, "Sanctuary" allows Sora to treat all Fusion Monsters he controls as "Frightfur" monsters. He then activates "Frightfur Fusion" to Fusion Summon a "Frightfur" Monster by banishing its Fusion Materials from his side of the field or his Graveyard. He banishes "Frightfuloid", treated as a "Frightfur" monster by its own effect, "Bear", and "Tiger" from his Graveyard to Fusion Summon "Frightfur Chimera" (2800/2000) in Attack Position. "Chimera" attacks and destroys "Darkwurm". The Pendulum Effects of "Zero" and "Infinity" reduce the damage to 0 and increase Z-ARC's LP by the same amount (Z-ARC 7000 → 8000). Sora Sets a card.
Turn 4: Z-ARC
Z-ARC Pendulum Summons the two copies of "Darkwurm" (1800/1200) from his Extra Deck in Attack Position. As a monster was Special Summoned alongside another Special Summoned monster while Aster controls a "Destiny HERO" monster, Aster activates his Set "D - Hyper Nova", destroying all monsters that were Special Summoned this turn. As a card or effect that would destroy an opponent's monster was activated while he controls a face-up "Frightfur" monster, Sora activates his Set "Frightfur Mad Parade", destroying all cards on Z-ARC's field and inflicting 500 damage to him for each monster destroyed. "Zero", "Infinity", and the two "Darkwurm" are destroyed (Z-ARC 8000 → 6000). As his cards were destroyed, Z-ARC activates the effect of "Astrograph Sorcerer" in his hand, Special Summoning it (2500/2000) in Attack Position and returning all cards destroyed this turn in the same Zone they were in before they were destroyed. Z-ARC places "Zero" ( 0) and "Infinity" ( 13) back in his Pendulum Zones and Special Summons the two copies of "Darkwurm". Z-ARC activates the second effect of "Astrograph Sorcerer", letting him banish "Dark Rebellion Xyz Dragon", "Clear Wing Synchro Dragon", "Starving Venom Fusion Dragon", and "Odd-Eyes Pendulum Dragon" from his Deck, Extra Deck, field, and Graveyard to Integration Summon "Supreme King Z-ARC" from his Extra Deck (4000/4000) in Attack Position.
As "Z-ARC" was Summoned, its effect activates, destroying all monsters Sora and Aster control and inflicting damage to them equal to the total ATK of the monsters destroyed, but "Z-ARC" cannot attack the turn this effect was activated. "Dystopia" and "Chimera" are destroyed (Aster 2600 → 0, Sora 4000 → 0).
In the dub, when Aster Phoenix and Sora Perse started their Duel against Z-ARC, the computer in their Duel Disks stated that "Crossover" has been activated. Originally, Aster and Sora didn't have "Crossover" available, and it was activated when Shay and Kite joined the Duel.