Polymerization is a normal-type spell card in the Yu-Gi-Oh! trading card game. This card allows its user to Fusion Summon one Fusion Monster from their Extra Deck by fusing monsters from their hand or their side of the field. As it is the main way to summon most of the powerful Fusion Monsters, it is a staple in the deck of many main characters, including Muto Yugi and Yuki Judai.
