Polymerization

 One of the monsters in this card's artwork has since been retroactively revealed to be Synchro Fusionist.

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This card, or some sort of twisted version of its artwork, appears in the artwork of Fusion Recovery, Fusion Substitute, Revoke Fusion, Instant Fusion, Mixeroid, Double Fusion, Anti-Fusion Device, Hope for the Future, and Fusion Destruction.

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In chemistry, polymerization is the process of fusing two or more molecular units into larger chains of units called polymers. This is similar to Yu-Gi-Oh! as two or more monsters are being combined to form a new, stronger monster.

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This card has the most errata of any card in the OCG, with nine different erratas.

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This card's name's Japanese pronunciation is the basis for Yugo being mistaken as an ally of the Fusion Dimension in Yu-Gi-Oh! ARC-V.

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There are 14 cards in the game that specifically search for Polymerization, more than any other card in the game. There are also 8 more that can search for any card with Polymerization in its name, such as Super Polymerization.

Polymerization

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OCG Rulings

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You can use face-down monsters as Fusion Material Monsters.: Is it possible to use face-down monsters on the field as Fusion Material Monsters?

The effect of "Fusion Recovery" targets a total of two cards: one "Polymerization" and one Fusion Material Monster.: Spell Card > Fusion Recovery

When Fusion Summoning with "Polymerization", you can use a monster which is face-down on the field as a Fusion Material monster. When doing so, you must show it to your opponent to confirm that it is a proper Fusion Material.: When Fusion Summoning, can you use a face-down monster as a Fusion Material?

The effects of "Thunder King Rai-Oh", "Black Horn of Heaven", "Solemn Judgment", and similar cards cannot negate a Special Summon by another card effect.: Please explain what Special Summons can and cannot be negated by the effects of "Thunder King Rai-Oh", "Solemn Judgment", and so on.
Example: Cards like "Thunder King Rai-Oh" cannot negate the Special Summon by the effects of "Monster Reborn" or "Polymerization". However, "Solemn Judgment" can also negate the activation of a Spell/Trap Card, so it can negate the activation of "Monster Reborn" or "Polymerization" itself.

King of the Swamp: If you have no copy of "Polymerization" in your Deck, you cannot activate the effect of "King of the Swamp", and you cannot activate "Fusion Sage".: Can the effect of "King of the Swamp" be activated if you have no "Polymerization" in your Deck?

Macro Cosmos: You can still activate cards like "Polymerization" or "Power Bond" and Fusion Summon while the effect of "Macro Cosmos" is active and removing from play the Fusion Material Monsters instead of having them sent to the Graveyard. If "Polymerization" is activated while "Macro Cosmos" is active, then the Fusion Material Monsters to be sent to the Graveyard will be removed from play instead, and the Fusion Monster will still be Fusion Summoned from the Extra Deck

Previously Official Rulings

Mentions in Other Rulings

Disturbance Strategy: You can also chain "Disturbance Strategy" to "Polymerization" and, if the opponent no longer has the Fusion Material Monsters (if they were in his/her hand for example) then the effect of "Polymerization" disappears.

Fusion Gate: Fusion Monsters Special Summoned without "Polymerization" while "Fusion Gate" is on the field are still considered properly Summoned by a Fusion Summon. So they may be the target of "Monster Reborn", "Call of the Haunted", etc. (This does not apply to Fusion Monsters Special Summoned by the effects of other cards, such as "Magical Scientist" or "Summoner of Illusions".)

Fusion Recovery: You can use "Fusion Recovery" to retrieve a Fusion Material Monster that was Summoned with "Power Bond", "Fusion Gate", "Polymerization" etc.

Fusion Recovery: "Fusion Recovery" targets 1 monster and 1 "Polymerization" in the Graveyard (so it will be negated by "Necrovalley" or "The End of Anubis").

Horn of Heaven: "Horn of Heaven" cannot be used to negate a Special Summon that results from a Spell, Trap, or effect of an Effect Monster Card. You cannot use "Horn of Heaven" to negate a Special Summon from "Polymerization" .

King of the Swamp: You can only get 1 copy of "Polymerization" when you discard "King of the Swamp" from your hand.

King of the Swamp: You can activate the effect of "King of the Swamp" even if all 3 of your "Polymerization" cards are in your Graveyard.

King of the Swamp: If you use "King of the Swamp" as Fusion Material from your hand, you do not get to activate its effect to search your Deck for "Polymerization".

Macro Cosmos: You can activate "Polymerization" while "Macro Cosmos" is active on the field because sending Fusion Material Monsters to the Graveyard is an effect of "Polymerization" and not a cost.

Non-Spellcasting Area: While "Non-Spellcasting Area" is active, you cannot use face-up monsters on the field, except Effect Monsters, for "Polymerization" or Ritual Spell Cards.

Prohibition: If a Fusion Monster is declared with "Prohibition", it cannot be Fusion Summoned from the Extra Deck with "Polymerization". If a Fusion Material Monster is declared, it cannot be used in a Fusion Summon.

Soul Exchange: You cannot use "Soul Exchange" for "Polymerization" because "Polymerization" does not use Tribute.

The Dark - Hex-Sealed Fusion / The Earth - Hex-Sealed Fusion / The Light - Hex-Sealed Fusion: When you use this monster's second effect, you also get its first effect. So this monster enables you to perform a Special Summon of a Fusion Monster without "Polymerization", etc., and also acts as a "substitute" for one of the Fusion Material Monsters.

The Dark - Hex-Sealed Fusion / The Earth - Hex-Sealed Fusion / The Light - Hex-Sealed Fusion: Using the second effect of this monster does not "properly" Fusion Summon the Fusion Monster. So it cannot be revived from the Graveyard, etc. If you use "Polymerization" then you can revive the Fusion Monster from the Graveyard, even if you used this monster as a "substitute" Fusion Material Monster.