Basically a lot of things similar to the OCG/TCG.
Regarding the Extra Deck
Cards in the Extra Deck Zone are placed face-down. The maximum number of cards you can have in the Extra Deck is 15, but you don’t need cards in your Extra Deck to Duel. You can only place Fusion Monsters in the Extra Deck. Also, you can only have up to 3 copies of the same card in your Extra Deck. You can check your Extra Deck’s contents in the middle of a Duel
Legends:
It has been updated to clarify that you can only have one Legend among the cards in your Main Deck and Extra Deck combined.
FAQ
Q. What positions can I place a Fusion Summoned Fusion Monster?
A. Place it in a Monster Zone in either Face-up Attack Position or Face-up Defense Position.
Q. If a Fusion Monster is destroyed, what happens to it.
A. Just like any other monster it is sent to the Graveyard.
Q. Can Fusion Monsters be Special Summoned from the Graveyard?
A. They Can
Q. Is a Monster Fusion Summoned from the Extra Deck a “Special Summoned Monster”?
A. Yes, it is. A Fusion Summoned monster is treated as a Special Summoned monster.
Q. Is a Monster Special Summoned from the Graveyard a Fusion Summoned monster.
A. There’s a difference. Special Summoned monsters are not the same inherently as a Fusion Summoned monster.
Q. Can you use face-down Defense Position monsters as materials if you Fusion Summon using the Spell Card “Fusion”?
A. No, you cannot.
Q. Can you use monsters in your hand as materials if you Fusion Summon using the Spell Card “Fusion”?
A. No, you cannot.
Q. When you activate a card with a Requirement along the lines of “[Requirement] You can activate this by shuffling 1 card from your Graveyard into the Deck”, can you shuffle a Fusion Monster back into the Extra Deck to activate it?
A. Yes.
Q. When you activate a card with a Requirement along the lines of “[Requirement] You can activate this by placing 1 card from your Graveyard on the bottom of the Deck”, can your turn a Fusion Monster back into the Extra Deck to activate it?
A. Yes, you can. Since there is no strict order to the Extra Deck, you don’t HAVE to place it on the bottom of the Extra Deck.
Q. Can you choose a Fusion Monster if you activate an effect along the lines of “[Effect] Choose 1 monster in your opponent’s Graveyard and shuffle it into the Deck.”?
A. Yes, you can. In that case shuffle the Fusion Monster into the Extra Deck.
Q. Can you choose a Fusion Monster if you activate an effect along the lines of “[Effect] Choose 1 monster in your opponent controls and return it to the owner’s hand”?
A. Yes, you can. In that case shuffle the Fusion Monster into the Extra Deck.
Q. Is a Fusion Monster without an effect a Normal Monster?
A. They’re different things. That monster is a “Fusion Monster without an Effect”. (It is neither treated as a Normal Monster nor an Effect Monster.)
