Card Game Rules you may not have known! - (Yu-Gi-Oh!)

 

    When playing Yu-Gi-Oh!, one of the major playstyles of cards and archetypes is the use of Fusion monsters. Fusion is achieved by having a card within your Extra Deck that has monsters listed that it needs to be fused together, typically with the basic polymerization card, as shown above. Fusion monster cards are typically purple in color, and are fairly powerful, due to being difficult to bring out onto the battlefield. Decks that use fusion monsters that are currently popular in the game space are: Shaddolls, HEROs, and Ancient Gear Decks. The reason why fusion decks are hard to use is due to the conditions of pulling off a fusion summon. Typically a fusion summon must be performed by having the required fusion spell or trap card in your hand or on the field, the required monster in your extra deck, and having the required monsters needed to summon the monster in your hand or on your field already. This means that your opponent can block your fusion summon with the use of traps or spells that negate other traps or spells, or ones that destroy monsters in the hand or on the field. 

Polymerization card (Anime Style) created by: Polymerization (4kids based card) by alphiecross on DeviantArt