A Duelist's Main Deck is the pile of cards that is placed on the Deck Zone. The Main Deck is, essentially, all the cards the Duelist will be playing with in a Duel. This Deck contains all of the cards (Trap, Spell and Monster) that the Duelist may use, excluding Fusion, Synchro, and Xyz monsters, which are kept in a seperate "Extra Deck". KUD Most card effects that allow you search your Deck and select one or more card(s) normally include shuffling your Deck, this is to maintain fair play.
To be legal, the Main Deck must be between 40 to 60 cards with most decks containing approximately 40 cards. Most experienced Duelists will argue that you should stick to the minimum because it increases the chances of you drawing your best card(s). Another point of view is that a large Deck, with cards that allow you to search out ones you need ("Terraforming" or "Dark Magic Curtain") may also work well. If a deck focuses on one strategy, such as a Burn Deck, and holds no real critical cards, then a lot of cards may be helpful for more 'ammo'. Certain cards like "Mystic Tomato" or "Gold Sarcophagus" are also more useful in a larger Deck.
The Extra Deck and Side Deck each have an upward limit of 15 cards, but neither counts towards the count of the Main Deck.
Rulings from Konami regarding the Main Deck include:
- No cards can be placed below the line of your Main Deck.
- You cannot turn it sideways.
LOL CARDGAMES IN SPACE ! EXTRA DECK :D