Gemini monsters (Japanese: デュアルモンスター Dyuarumonsutā "Dual Monster") are Effect Monsters with the ability "Gemini". Gemini monsters are treated as Normal Monsters with no usable effects when first placed on the field, but can gain usable effects if they are Normal Summoned while already face-up on the field.
Gemini monsters debuted in Tactical Evolution. The "Chemicritter" archetype is heavily focused on, and almost completely composed of, Gemini monsters. The "Red-Eyes" archetype also contains several Gemini monsters.
All Gemini monsters share the following two effects:
- This card is treated as a Normal Monster while face-up on the field or in the GY.
- While this card is a Normal Monster on the field, you can Normal Summon it to have it become an Effect Monster with these effects.
● [Individual Effects]
Gemini monsters treated as Normal Monsters can be Normal Summoned while already face-up on the field (this Normal Summon is referred to as a Gemini Summon in some video games). Normal Summoning a face-up Gemini monster is still a Summon, so it can be negated by cards and effects that negate Normal Summons. Unlike when being Normal Summoned from the hand, Tributes are not required to Normal Summon a Level 5 or higher Gemini monster that is already on the field.
Cards and effects that are targeting or affecting the Gemini monster (such as Equip Spell Cards) remain in effect after the Summon. If a Gemini monster that has gained its effects is flipped face-down, it will become treated as a Normal Monster again when it is flipped back up.
Some card effects (such as "Supervise" and "Superalloy Beast Raptinus") allow Gemini monsters to gain their effects without being Normal Summoned. If these effects stop applying, Gemini monsters that only gained their effects due to one of these card effects (i.e. had not been Normal Summoned while face-up on the field) lose their effects again.
Gemini monsters require the player using their once-per-turn Normal Summon to grant an already summoned monster its effects. Since all non-Gemini effect monsters do not require such a cost to "unlock" their effects, the effects that Gemini monsters provide must outweigh their opportunity cost for the trade to be valuable. Unfortunately, due to their often old designs, most Gemini monsters do not have powerful enough effects to make up for their Normal Summon cost.
Because of their hefty costs and weak effects, most Gemini playstyles heavily depend on Gemini support cards to offset their costs and enable certain power cards that specifically require Gemini monsters. Key Gemini support cards include:
- "Gemini Spark", a Quick-Play Spell that can be used to make a 2-for-2 trade of tributing 1 Gemini monster, destroying 1 opposing card, and drawing a card; it can be used to dodge some targeted effects to maximize advantage.
- Cards that immediately grant Gemini monsters their effects, such as "Supervise" and "Superalloy Beast Raptinus"
- "Catalyst Field", which grants Tribute-free Normal Summons, double Normal Summons, and removal effects for Gemini decks
- "Chemicritter", which provides general support to Gemini monsters
- "Gemini Ablation", which Special Summons Gemini monsters from the Deck, with their effects enabled
Gemini monsters also benefit from some Normal Monster support, due to being treated as Normal Monsters while first summoned onto the field and in the GY. However, key Normal Monster consistency cards like "Unexpected Dai" do not work on Gemini monsters, because they are not treated as Normal Monsters in the hand or Deck.
Because many Gemini monsters belong to other archetypes, Gemini decks often benefit from other archetypal support as well.
Neos Alius Beatdown
- The heavy cost inherently involved within the Gemini playstyle means that Gemini decks are extremely fragile, and simple disruptions can often completely shut down the deck's ability to play, as each player only has 1 Normal Summon per turn.
- Most Gemini monsters, even after being Normal Summoned and gaining their effects, have effects that are merely equal to the effects of other contemporary non-Gemini effect monsters, meaning that they do not make up the opportunity cost.
Effect Gemini Monster ("Red-Eyes Black Flare Dragon")
In the anime
- "Phoenix Gearfried" is on the poster for the World Racing Grand Prix in Yu-Gi-Oh! 5D's.
- "Gigaplant" appears in a flashback of Akiza Izinski's past in Yu-Gi-Oh! 5D's.
- "Crusader of Endymion" has been seen played by random Duelists in "Operation: Capture Yeager II!" as well as Yu-Gi-Oh! ZEXAL episode 0011: "Go With the Flow, Part 1".
- Multiple copies of "Ancient Gear Knight" are used by members of Duel Academy during their invasion of Heartland City in Yu-Gi-Oh! ARC-V episode 03636: "Sora's Secrets: Part 2".
- Rin used "Lucky Pied Piper" in a flashback in Yu-Gi-Oh! ARC-V episode 05454: "City 'Scape".
- "Future Samurai" appeared in a flashback, used by No.9 in Yu-Gi-Oh! ARC-V episode 126126: "An Evil Ascends".
- The first Gemini monster that made an appearance in a proper Duel is "Phoenix Gearfried" in Yu-Gi-Oh! VRAINS episode 06161: "Darkness Dawns", under the ownership of Theodore Hamilton.
- The shared effect to Normal Summon a Gemini monster already face-up on the field is referred to as a Gemini Summon (Dual Summon in Japanese) in some video games.
- There are no Beast-Warrior, Cyberse, Dinosaur, Psychic, or Wyrm-Type Gemini monsters.