History GeniusBonus / YuGiOh

* The card [[http://yugipedia.com/wiki/True_King_of_All_Calamities "True King of All Calamities"]], specifically its Japanese name. A Level 9 Xyz monster, it can be summoned using the three "True King" cards: "True King Agnimazud, the Vanisher", "True King Bathrastos, the Fathomer", and "True King Lithosagym, the Disaster". Its Japanese name references the combination of those three titles, "V.F.D.". This is also an abbreviation of "Vicarius Filii Dei", or "Representative of the Son of God", a title said to have been given to Saint Peter, the canonical first Pope. However, this title was also read by opponents as proof that the Pope was a representative of {{Satan}}... in the Japanese name, the "V.F.D." is read as "[[NamesToRunAwayFromReallyFast The Beast]]", which adds another GeniusBonus as the title above can also be calculated to sum to [[NumberOfTheBeast 666]].

** Amnael's Alchemy deck contains six "Alchemy Beast" monsters and Golden Homunculus, reflecting the seven base metals that ancient world alchemists recognized. Meanwhile his Spell cards reference the four stages of the alchemical process, which each had their own name and associated color that are accurately represented by Amnael's cards. When he transitions to his Helios series (which have three forms of escalating power), it's a reference to Hermes Trismegistus, "thrice-greatest Hermes", the man who created the foundations of Hermeticism. Hermeticism teaches there are three parts to how the universe operates -- Alchemy, Astrology, and Theurgy (the study of how the Gods work and a type of magic that is counterpart to Goetia, the study of Demons). This symbolizes that Amnael has mastered Alchemy and Astrology and now seeks to acquire the power of the Sacred Beasts/Phantom Demons. The fact his deck contains no overt references to Theurgy, though, shows that such power is beyond his grasp.

*** Nigredo, the black, putrefying stage: Nightshroud's plot to break down humanity into a homogenous base form within his world of darkness.

*** Rubedo, the red, ultimation stage: The fight over the sacred beasts and their ability to offer eternal youth, one of the end goals of alchemy. Also Jaden being in the red dorm, representing his role as an ultimate alchemist.

** Yubel appears to be based on the rebis, a symbolic {{hermaphrodite}} used in alchemy as a metaphor for the fusion of nature's duality.

*** Notably, this also serves as a contrast to the evolution of Jaden's deck, who Amnael correctly believes will surpass him. First there's Electrum/Elixier, representing Jaden's mastery of alchemy, being the fusion of all four basic elementals to form the ultimate E-Hero, and named after both of alchemy's end goals: the creation of precious metals (electrum being an alloy of gold and silver), and the creation of the elixir of eternal life. Jaden then goes on to acquire the Neos and Neospacian series, creatures from the stars representing astrology. Finally, Jaden realises theurgy through Divine Neos, proving himself as a master alchemist of all three disciplines.

* The names of the members of Yliaster -- Paradox, Aporia, and Antinomy -- are named after logical fallacies and impossibilities in Greek philosophy. Fitting given that Yliaster is trying to cause a TemporalParadox. Each name fits their role too:

** Ib (Heart): Yuya, [[TheHeart the compassionate, friendly one]]. The Heart is what would be weighed in the afterlife to determine your fate, fitting with Yuya's Pendulum ''Scales''.

** In particular, viewers may notice that the final duel between Jaden and Yubel closely mirrors a Jewish wedding ceremony. Elements include: The marriage contract and dowry (Spell Chronicle and its related cards), a minimum of two witnesses unrelated to the couple (Syrus and Ojama Yellow), the placing of the veil (Rainbow Veil), the bride circling the groom (Yubel's thorns), drinking from the cup of life (Air Hummingbird's effect), the seven blessings (Rainbow Neos), the breaking of the glass (Duel Academia's windows cracking), all culminating in Jaden and Yubel reaffirming their love as they're united forever by Super Fusion, before retreating away alone together like in the Yichud.

** Aporia: The confusion resulting from different pieces of evidence supporting different conclusions. Each of Aporia's three components are a different take on the same person.

*** Notably, this also serves as a contrast to the evolution of Jaden's deck, who Amnael correctly believes will surpass him. First there's Electrum/Elixier, representing Jaden's mastery of alchemy, being the fusion of all four basic elementals to form the ultimate E-Hero, and named after both of alchemy's end goals: the creation of precious metals (electrum being an alloy of gold and silver), and the creation of the elixir of eternal life. Jaden then goes on to acquire the Neos and Neospacian series, creatures from the stars representing astrology. Finally, Jaden masters theurgy through Divine Neos, proving himself as a perfect alchemist of all three disciplines.

*** Then there's the monster that defeats him, Electrum/Elixier, also a reference to alchemy, being the fusion of all four basic elementals to form the ultimate E-Hero, and named after both of alchemy's end goals: the creation of precious metals (electrum being an alloy of gold and silver), and the creation of the elixir of eternal life.

*** Rubedo, the red, completion stage: The fight over the sacred beasts and their ability to offer eternal youth, one of the end goals of alchemy. Also Jaden being in the red dorm, representing his role as the ultimate alchemist.

* Rex's Inca deck is full of monsters symbolizing and/or based on Incan deities; for instance, Inti is the Incan sun god and Quilla is the moon goddess. When the archetype got new support in the real life card game, [[https://twitter.com/YuGiOh_OCG_INFO/status/1131303721768542208 Envoy Oracle of Ascator]] and [[https://twitter.com/YuGiOh_OCG_INFO/status/1131484916187844609 Reaper Oracle of Supay]] were revealed on the Japanese Twitter account at 6 am and 6 pm, Japan standard time, fitting for representing the sun and moon.

** In particular, viewers may notice that the final duel between Jaden and Yubel closely mirrors a Jewish wedding ceremony. Elements include: The marriage contract (Spell Chronicle), the placing of the veil (Rainbow Veil), the bride circling the groom (Yubel's thorns), drinking from the cup of life (Air Hummingbird's effect), the seven blessings (Rainbow Neos), the breaking of the glass (Duel Academia's windows cracking), all culminating in Jaden and Yubel reaffirming their love as they're united forever by Super Fusion, before retreating away alone together like in the Yichud.

** Yubel appears to be based on the rebis, a symbolic {{hermaphrodite}} used as a metaphor for the fusion of nature's duality.

* The series also indulges heavily in symbology from Judaism. (What's the main characters Japanese name again?)

*** Citrinitas, the yellow, awakening stage: Yubel awakening Judai's past and powers (giving him yellow eyes as the Supreme King).
*** Rubedo, the red, completion stage: The fight over the sacred beasts and their ability to offer eternal youth, one of the end goals of alchemy. Also Judai being in the red dorm, representing his role as the ultimate alchemist.

* Saiou's Tarot themed Arcana Force deck often has symbolism in his cards that reflects either what is happening in the duel or something about his opponent. For instance, against Manjoume, he uses Suit of Sword X and it stops upright; this represents defeat and the anguish and despair that accompanies loss, but there is also a glimmer of hope for things to improve, like how Jun has repeatedly lost to Judai and is doubting his skills, but he can find new purpose if he joins the Society of Light. When Saiou claims his cards give him insight on his opponent, he's completely serious.
* Kabukid (Orlando in the dub) plays a Kabuki deck with many references to the story of [[UsefulNotes/MusashiboBenkei Benkei]], a popular figure for Kabuki performances.

* Episode 19~20 has Kyuando using a quiz gimmick, where the action cards require you to answer correctly to get a positive result. One of the questions is to prove UsefulNotes/FermatsLastTheorem, which wasn't proven until almost ''four hundred years'' after it was first proposed.

* Lightning's quotes to Blood Shepherd before their fight is taken from the Literature/TheDivineComedy:

* Genome's obsession with DNA may look out of place in a group of programmers, but his deck is a shoutout to [[https://en.wikipedia.org/wiki/Genetic_algorithm Genetic Algorithms]], an algorithm inspired by Charles Darwin's theory of Natural Evolution that imitates the process of natural selection, and [[https://en.wikipedia.org/wiki/Genetic_programming Genetic Programming]], which in layman's terms, applies the algorithm to simulate breeding in programs via Darwinian evolution to find the most optimal programs for the next generation, which also fits his superiority complex for DNA.