2 "Magician" Pendulum monsters
Must first be Fusion Summoned with the above materials. Once per turn: You can target 1 "Magician" card in your Pendulum Zone; destroy it, then 1 monster your opponent controls loses ATK equal to that monster's ATK. If a "Magician" card in your Pendulum Zone is destroyed by another card's effect: You can choose a Pendulum monster in your Extra Deck or GY and place it in your Pendulum Zone. You can only use this effect of "Spacetime Magician" once per turn.
Everyone knows that Arc-V's ending felt rushed and awful. But my theory (backed up by anecdotal evidence of artists behind the scenes saying as much) is that the damage extended much further back, to the supporting cast collectively jobbing to Zarc at least. GIven how Pendulum Evolution gave us a radically redesigned Astrograph Sorcerer (anime Astrograph wasn't even a Pendulum monster, Zarc's signature mechanic), the card game original Chrongraph Sorcerer and all of these cards that center around those two, it almost makes me think that those cards were intended to be used by Zarc, despite the Supreme King cards existing. With the Dragon magicians being treated as their respective parts and Astrograph and Chronograph being able to summon Z-ARC, the set built a ton out of exactly two cards shown in the anime.
Based on that, I figured that it's entirely conceivable that two duels could've happened in the anime, but they ran out of budget or something went wrong in production: Zarc would fight the rest of the cast until the deus ex machina shows up, and also fights the Yu boys inside his head. It didn't make sense that they would circulate the four major characters out of the show completely (even though Zarc is voiced by Yuya's seiyuu in Japan). It seems extremely farfetched, but it explains why the support is so plentiful for that particular deck.
The card in particular is designed to be part of the trio that consists of this, Timestar Magician, and Enlightenment Paladin, as three monsters Zarc summons during his duel against the Yu boys. During the duel he manages to get the four magicians needed in his extra deck to summon Zarc, using this and Timestar specifically to dig the pieces out. It's also a big synchro/xyz/fusion board that would demonstrate Zarc's power (because that's what they did with Reiji when they wanted to show him off.
Arc-V had a ton of setup, and I feel like a lot of it was planned way ahead of time and scrapped (feel free to hear my rant on COTD being hastily slapped together at the last minute whenever ou want!) because of poor management and budgetary concerns. I at least want to fill the picture in my headcanon to make me feel better, if nothing else.