"Showdown in the Sewers", known as "The Final Trigger" in the Japanese version, is the thirty-first episode of the Yu-Gi-Oh! VRAINS anime. It first aired in Japan on December 13, 2017 and aired on Teletoon on December 15, 2018. It became available with official subtitles via Crunchyroll on the same day.
Turn 2: Varis
Varis Normal Summons "Gateway Dragon" (1600/1400). He then activates the effect of "Gateway Dragon" to Special Summon a Level 4 or lower DARKDragon monster from his hand. He Special Summons "Sniffer Dragon" (800/400). As it was Special Summoned, Varis activates the effect of "Sniffer Dragon" to add another copy of "Sniffer Dragon" from his Deck to his hand. Varis activates the effect of "Defrag Dragon" in his hand, sending another monster from his hand to the GY to Special Summon it. He sends "Background Dragon" to the GY to Special Summon "Defrag Dragon" in Attack Position (1000/600). Varis uses "Gateway Dragon" and "Sniffer Dragon" to Link Summon "Twin Triangle Dragon" (1200/LINK-2/↓→) to the Extra Monster Zone. Varis activates the effect of "Twin Triangle Dragon", paying 500 LP to Special Summon a Level 5 or higher monster in his GY to a zone it points to, but it cannot attack this turn and has its effects negated (Varis: 4000 → 3500 LP). He Special Summons "Background Dragon" (1600/1800) to the bottom Link Point of "Twin Triangle Dragon". Varis uses "Twin Triangle Dragon", "Background Dragon", and "Defrag Dragon" to Link Summon "Topologic Bomber Dragon" (3000/LINK-4/↑↙↓↘) to the Extra Monster Zone. Varis Sets a card.
"Bomber Dragon" attacks "Altergeist Marionetter" (1600/1700). As Varis' monster attacked while she controls an "Altergeist" monster, Ghost Gal activates the effect of "Altergeist Kunquery", Special Summoning it (0/2400), then negating the attack. As "Kunquery" was Special Summoned, Ghost Gal activates its effect, which lets her negate the effects of a monster Varis controls while "Kunquery" is on the field. She negates the effects of "Bomber Dragon".
Turn 3: Ghost Gal
Ghost Gal's hand contains "Altergeist Silquitous" and "Altergeist Materialization". Ghost Gal Normal Summons "Altergeist Silquitous" (800/1500). She activates the her face-down Continuous Trap Card "Altergeist Protocol". Ghost Gal activates the effect of "Silquitous", returning an "Altergeist" card she controls to her hand to return a card Varis controls to his hand. She returns "Protocol" to her hand, and returns "Bomber Dragon" to Varis' Extra Deck. Ghost Gal uses "Kunquery" and "Silquitous" to Link Summon "Altergeist Kidolga" (1000/LINK-2/←↓) to the Extra Monster Zone, then uses "Kidolga" and "Marionetter" to Link Summon "Altergeist Primebanshee" (2100/LINK-3/↓↘→) to the Extra Monster Zone. Ghost Gal activates her face-down Trap Card "Altergeist Materialization" to Special Summon an "Altergeist" monster from her GY, and equip "Materialization" to that monster. When "Materialization" leaves the field, that monster is destroyed. She Special Summons "Kidolga". Ghost Gal Sets two cards.
"Primebanshee" attacks Varis directly (Varis 3500 → 1400 LP). As another "Altergeist" monster inflicted battle damage to Varis, Ghost Gal activates the effect of "Kidolga", which lets her Special Summon a monster in Varis' GY to a zone "Kidolga" points to, but it cannot attack unless "Kidolga" attacked that turn. She Special Summons "Twin Triangle Dragon" to the left Link Point of "Kidolga". "Kidolga" attacks Varis directly (Varis: 1400 → 400 LP). "Twin Triangle Dragon" attacks Varis directly, but Varis activates an unseen Trap Card which destroys "Kidolga", "Primebanshee" and "Twin Triangle Dragon". As "Primebanshee" was sent from the field to the GY, Ghost Gal activates its effect, adding an "Altergeist" card from her GY to her hand. She adds "Marionetter". Ghost Gal activates her Skill "Secret Cure", to excavate cards from her Deck, until she excavates a monster. That monster is added to her hand, both players gain LP equal to its ATK, and all other cards are sent to the GY. She excavates "Kunquery" and adds it to her hand.
Turn 4: Varis
Ghost Gal activates her face-down Continuous Trap Card "Altergeist Protocol". "Protocol" prevents the activation and effects of "Altergeist" cards on Ghost Gal's field from being negated. When Varis activates a monster effect, Ghost Gal can send another face-up "Altergeist" card on the field to the GY to negate the activation and destroy that monster. As Ghost Gal activated a Trap Card, Varis pays half his LP to activate "Red Reboot" from his hand (Varis: 400 → 200 LP), to negate the activation of that Trap Card and re-Set it, then Ghost Gal can Set a Trap directly from her Deck. "Red Reboot" also prevents Ghost Gal from activating Trap Cards for the rest of the turn. Ghost Gal Sets "Altergeist Camouflage". As he controls no monsters, Varis activates the effect of "Background Dragon" in his GY to Special Summon itself and a Level 4 or lower Dragon monster from his hand in Defense Position, but "Background Dragon" is banished when it leaves the field. He Special Summons it (1600/1800) and "Sniffer Dragon". As "Sniffer Dragon" was Special Summoned, Varis activates its effect to add another copy of "Sniffer Dragon" from his Deck to his hand, which he subsequently Normal Summons.
At this point, Varis enters the Data Storm. Varis activates his Skill "Storm Access", which allows him to randomly access a card from a Data Storm when his LP is 1000 or less. Varis obtains "Topologic Trisbaena" and adds it to his Extra Deck.
Varis uses "Background Dragon" and both copies of "Sniffer Dragon" to Link Summon "Topologic Trisbaena" (2500/LINK-3/↙↑↘) to the Extra Monster Zone. Varis activates the effect of "Defrag Dragon" in his GY, banishing three other monsters with the same name from his GY to Special Summon it. He banishes three copies of "Sniffer Dragon" and Special Summons "Defrag Dragon" in Defense Position (1000/600) to the bottom-left Link Point of "Trisbaena". As a monster was Special Summoned to a zone "Trisbaena" points to, its effect activates, banishing that monster and all Spells/Traps on the field, then inflicting 500 damage to Ghost Gal for each of Ghost Gal's cards banished by this effect (Ghost Gal: 4000 → 2500 LP). "Trisbaena" attacks Ghost Gal directly (Ghost Gal: 2500 → 0 LP).
The following cards appeared in this episode. Cards in italics debuted here.