"Gem-Knight" (ジェムナイト Jemunaito) is an archetype that was released in Duel Terminal - Vylon Descends!!. They are used by Julia Krystal in the Yu-Gi-Oh! ARC-V anime.
All "Gem-Knight" monsters are EARTH, whereas their Type varies between Pyro, Thunder, Aqua, or Rock, as well as a few Fairy, in keeping with the cardinal elements: fire, wind, water and earth, respectively. "Gem-Knights" are further subdivided into trios: each Type includes a Normal member, a Gemini member, and a Fusion member.
All members of this archetype are named after different minerals. Aesthetically, they appear to be a synthesis of Jesse Anderson's "Crystal Beasts" and Jaden Yuki's "Elemental HERO" cards, possibly as an homage to their friendship in the anime. This is evidenced in cards such as "Gem-Knight Fusion", whose artwork is clearly a merging of "Crystal Release" and "Miracle Fusion".
In terms of playstyle, "Gem-Knight" monsters focus on rapidly and repeatedly Fusion Summoning their boss monsters by searching and recycling Fusion Spells and Materials. Their core Fusion Spell, "Gem-Knight Fusion", can return itself from GY to the hand by banishing 1 "Gem-Knight" monster from GY, and "Gem-Knight Obsidian" and "Gem-Knight Lazuli" can both recycle "Gem-Knight" Normal Monsters.
Their team symbol is a jewel droplet adorned with gold trim and two small, arced points. Its color varies according to the monster or object to which it is attached.
A group of warriors endowed with the power of minerals, the "Gem-Knights" value honor above all else and disapprove of battle for the sake of battle. At the provocation of the barbaric "Laval", however, they are forced to take up arms and protect the clans from their wanton destruction. However, the "Steelswarm" begin to invade the surface land, intending to take over. The Gem-Knights join up with the other clans in a temporary union spearheaded by the "Vylons". Along the way, they obtain new powers with which to resist the "Steelswarm". Although the "Steelswarm" are quickly dispatched, conflict is far from over. The "Vylons" decide to exterminate the clans in order to prevent future wars.
The clans once more band together in order to halt the "Vylon", but it is the collaboration between the "Gem-Knights" and "Gishki" to whom credit for their eventual victory goes: "Gem-Knight Pearl" is the downfall of the "Vylon". After the "Vylons" are driven back, the alliances between clans once again dissolve.
The "Gishki" immediately resume their invasion of "Mist Valley", which had been their main objective pre-"Steelswarm". In order to obtain resources from the Valley, the "Gishki" enact a genocide on the "Gusto". The Gem-Knights intervene to rescue the remaining "Gusto".
When the "lswarm" virus begins to spread across the Duel Terminal world, the Gem-Knights join the "Gusto" in a prayer for the "Constellar," a legendary band of divine warriors, to aid them. The "Constellar" may not be strong enough to resist the "lswarm" army alone, as the "Gishki" clan falls to the virus. Knowing this, the "Gem-Knights" fuse into the most powerful Gem-Knight.
"Cairngorgon, Antiluminescent Knight" appears to be a corrupted combination (probably by the "lswarm" virus) of "Gem-Knight Crystal", with parts of "Gem-Knight Zirconia" (right arm and left leg), "Gem-Knight Master Diamond" (left arm and right leg), and "Gem-Knight Prismaura" (damaged head).
The "Gem-Knight" archetype focuses on Fusion Summoning, accomplished with the use the archetype's many Fusion Summon-Spells/Traps and a wide array of recycling effects. The "Gem-Knight" Fusion Monsters each have their own effects, ranging from battle support, card destruction, to burn damage. They either require a specific "Gem-Knight" Normal Monster + any "Gem-Knight" monster as material, any "Gem-Knight" monster + any monster of a specific Type/Attribute as material, or 3 "Gem-Knight" monsters as materials.
Each of the archetype's Fusion Spell/Traps have different effects and have different levels of importance:
If your opponent controls a monster, Fusion Summons non-Rock "Gem-Knight" using Main Deck materials. Also applies Extra Deck Special Summoning restriction.
Conditionally valuable; despite also fusing from Deck, the restrictions on the card's effects forces a going-second beatdown-focused build.
Fusion Summons using GY materials, by banishing them.
Situational; less resource intensive, but Traps are delayed by one turn.
A key monster to the archetype's general strategy is their LINK 2 Link Monster "Gem-Knight Phantom Quartz", who is both a searcher for all archetypal cards, and also a Fusion Summoning extender able to Fusion Summon by shuffling materials in the GY or Banish Pile back into the Deck.
To quickly search out the archetype's monsters for use as Fusion materials, the archetype can make use of archetype-specific support (e.g.: "Gem-Armadillo"), Normal Monster support (e.g.: "Rescue Rabbit", "Unexpected Dai"), or Rock support (e.g. "Adamancipator Researcher", "Block Dragon"). "Crystal Rose" is an indirect searcher that can copy the name of any "Gem-Knight" monster in Deck (allowing it to be used as a Fusion or Link Material), and sends a "Gem-Knight" from Deck to GY, which can trigger floating effects. "Crystal Rose" and "Brilliant Rose" both have effects to Special Summon themselves and copy the name of a "Gem-Knight" monster, providing indirect searching for specific Fusion Materials.
To search out the archetype's Fusion Spells, external "Fusion" support cards like "Predaplant Darlingtonia Cobra" and "Predaplant Ophrys Scorpio" can be used, but "Phantom Quartz" alone can be used to search out "Gem-Knight Fusion", which can then be repeatedly used and reused. "Gem-Knight Quartz" can search out the powerful "Brilliant Fusion" and "Scatter Fusion", but has heavy restrictions attached to it.
Two key "Gem-Knight" monsters, "Gem-Knight Obsidian" and "Gem-Knight Lazuli", have non-once per turn effects that can recycle the player's monsters when sent to the GY, compensating for the costs of Fusion Summoning and extending the player's Fusion plays. "Gem-Knight Quartz" also has a GY recycle effect if it's used as a Fusion Material, albeit being once-per-turn only.
The intended strategy for the "Gem-Knight" archetype is likely a beatdown-focused one, focusing on Fusion Summoning multiple "Gem-Knight" Fusion Monsters, use them to remove the opponent's cards, and defeat the opponent with the high ATK of the Fusion Monsters.
This is an FTK strategy focused on using the effect of "Gem-Knight Lady Lapis Lazuli" and "Gem-Knight Master Diamond" (copying the effect of "Lady Lapis Lazuli") to repeatedly burn the opponent.
"Lady Lapis Lazuli" can inflict 500 damage to the opponent for each Special Summoned monster on the field. However, "Lapis Lazuli" can only be Special Summoned once per turn, necessitating the use of "Master Diamond" to copy the effect of "Lady Lapis Lazuli" and reuse its effects. Generally, Gem-Knight FTK aims to swarm the player's own field with monsters and activate the effects of "Lady Lapis Lazuli" once and "Master Diamond" twice to inflict around 8000 damage to the opponent, achieving an FTK.
This archetype appears to be based on the "Elemental HERO" archetype, since a few of their monsters share similar stats (Level/ATK/DEF) and poses with some "Elemental HERO" monsters.[1][2][3]
"Gem-Knight" monsters are all of one Attribute (EARTH), yet have a variety of Types, whereas the anime-based "Elemental HERO" monsters are all of one Type (Warrior), but of different Attributes.
In context of the "gem" theme, this archetype also appears to be based on the "Crystal Beast" archetype, since Jaden Yuki and Jesse Anderson were friends in the anime (who used an "Elemental HERO" Deck and a "Crystal Beast" Deck, respectively).
While the four "Gem-Knight" Normal Monsters are shown to be unarmed, the Fusion Monsters wield weapons befitting their stats and effects (or lack thereof):
The archetypal Spell Card "Brilliant Fusion" formed a splashable engine outside of "Gem-Knight" archetypal decks, as it can Fusion Summon "Gem-Knight Seraphinite" using materials from the Deck, granting an Extra Normal Summon, a Level 5 on-field monster, and mill a specific LIGHT monster into the GY.
