Dueling is the term used for playing the Yu-Gi-Oh! Cardgame, every player engages into a Duel or multiple duels called a Match.
 Setting Up
Both players will need a Deck containing 40 to 60 cards to play. The contents of your own deck are entirely up to you! A couple reminders, however:
- No more than 3 copies of a card may be played. Some have further limits (see Banlist) imposed on them, so be sure to check that your deck is obeying them before you play.
- Fusion Monsters, Synchro Monsters, and Xyz Monsters are not kept in your Deck and do not count toward the 40 card minimum or 60 card maximum. These are placed in the Extra Deck, an optional group of cards containing 0 to 15 cards that is placed face-down in the Extra Deck Zone. You can view your own Extra Deck at any time.
Once both players have their Decks prepared, they should shuffle their own, then their opponent's, and place their Decks face-down in their respective Deck Zones (where neither player can see their contents). Use a random method to determine who chooses player order. This can be done with a coin flip or die roll, for example, and whoever wins chooses who plays first.
After the first player is chosen, both players draw 5 cards from their Deck to be used as their starting [[Hand].
There are two primary Winning Conditions. If a player's Life Points are reduced to 0 (they start at 8000), their opponent wins the Duel. If a player cannot draw a card when they would be required to do so (either by an effect or at the start of their turn), their opponent wins the Duel.
It is also possible to win a Duel automatically by a card's built-in terms, such as those of Exodia the Forbidden One.
 Turn Structure
Players take turns making their big moves in a Duel, following the 6 Phases. These Phases are visited one at a time in a set order.
Standby Phase: Nothing specific happens here, though some effects will mention taking place at this time. If this is the case, follow those instructions.
Main Phase 1: Most moves are made here during a turn. Players can Summon or Set their monsters and Activate or Set their Spell Cards and Trap Cards during their own Main Phase 1. It's also possible to use Monster effects and change battle positions of Monsters on your side of the field. When you're done with Main Phase 1, you can choose to either enter your Battle Phase or proceed straight to the End Phase.
Battle Phase: You declare attacks with your monsters here in an effort to get rid of your opponent's monsters and reduce your opponent's Life Points. The player who goes first cannot conduct their Battle Phase on their first turn.
Main Phase 2: You can make the same moves here as you can in Main Phase 1. Your opponent's turn is coming up, so this is a good time to finish up any loose ends with your own turn and prepare for what your opponent might throw your way.
End Phase: At this point, you declare the end of your turn and address any effects that may occur during the End Phase. You also need to Discard cards from your hand if your hand contains more than 6 cards (this is the very last thing that happens during a turn).
Once a Phase has been passed, you cannot return to it that same turn, so be sure to get your business out of the way before moving on! After you're done with your turn, your opponent plays through their turn in the same fashion.
 More about the Main Phase
The big attractions about the Main Phase are Summoning or Setting your Monsters and Activating or Setting your Spell and Traps, so let's cover how these are done.
The creatures you call upon to attack your opponent and defend yourself are called Monsters. The Monsters that can exist in your hand will typically have Yellow or Orange borders, so they're easy to recognize. Once per turn, you can Normal Summon or Set 1 of these monsters from your hand.
When you Normal Summon a monster, you place it from your hand into one of your empty Monster Card Zones (there are 5 of these) face-up and vertical so both players can see what it is. A monster that is placed vertically is in Attack Position.
When you Set a monster, it is placed from your hand into one of your empty Monster Card Zones face-down and horizontal (sideways). Your opponent cannot look at it while it is face-down. A monster that is placed horizontally is in Defense Position.
Notice the number of stars under a Monster's name. These signify a monster's Level. A Level 1 to 4 monster can be Normal Summoned or Set right away without any trouble, but those of Level 5 or greater will run into a roadblock. They must be Tribute Summoned or Set.
A Tribute Summon is a specific kind of Normal Summon where you send a monster(s) on your side of the field to your Graveyard (the place where used cards go) to bring out that big monster from your hand. Level 5 or 6 monsters require 1 Tribute, where monsters of Level 7 or greater need 2 Tributes.
A Tribute Set, similarly, is just like a Set, but you need to follow the above requirements according to the monster's level. Both players will be able to see that monster's Level once it's face-up, so make sure you're honest with your number of Tributes!
In addition to your 1 Normal Summon or Set per turn, there are many cards that allow you to Special Summon. As long as you have the means to do so, you can Special Summon as many times as you like during your Main Phase. A monster that is Special Summoned is placed face-up in either Attack Position or Defense Position, whichever the summoning player wishes, unless stated otherwise. Much like there are multiple ways to Normal Summon or Set, there are several methods of Special Summoning.
The newest, easiest, and perhaps most odd kind of Special Summon yet is the Xyz Summon. Xyz (pronounced ik-seez!) Monsters have Black borders and reside in your Extra Deck, and you can access them any time as long as you control 2 (sometimes more) face-up monsters with the same Level.
Here's where it gets interesting. First, declare the Xyz Monster you wish to Xyz Summon, then take the matching monsters it lists as Xyz Materials and pile them up on top of each other! Place your Xyz Monster on top of this pile. The monsters you used as Xyz Materials are no longer treated monsters, but you can detach (send to the graveyard) them from the Xyz Monster to activate or otherwise use its special abilities.
Another common type of Special Summon is the Synchro Summon. Synchro Monsters (monsters with White borders that reside in your Extra Deck) are usually summoned this way.
Each Synchro Monster lists certain Monsters that must be sent from your side of the field to the Graveyard to summon it, called Synchro Material Monsters. Synchro Material Monsters must be face-up, and usually include 1 Tuner Monster and 1 or more non-Tuner Monsters. When adding the Levels of these monsters, the combination must be equal to the Level of the monster you wish to Synchro Summon. For example, if you want to Synchro Summon the Level 8 Stardust Dragon, you can use the Level 3 Junk Synchron and the Level 5 Turret Warrior. Simply declare the Synchro Monster you wish to Synchro Summon, send the right materials to your Graveyard, and place that Synchro Monster on your side of the field.
A Fusion Summon is another kind of Special Summon, and it is used to bring out a Fusion Monster (these have purple borders) from your Extra Deck.
Fusion Summons are performed by using a Spell card such as Polymerization and the Fusion Material Monsters listed on the Fusion Monster, which can be in your hand and/or on your field (battle positions don't matter) unless stated otherwise. As long as the Spell card is successfully activated, you send the Fusion Material monsters to your Graveyard and place the desired Fusion Monster on your side of the field. Unlike with a Synchro Summon, you do not declare which monster you intend to play or send away the materials in advance.
To Ritual Summon, activate an appropriate Ritual Spell from your hand while you have the matching Ritual Monster in your hand and enough monsters to Tribute for that Ritual Summon. The cards will, again, tell you what you need, but it will almost always be monsters who's total levels are equal or greater to that of the Ritual Monster. Tributes for a Ritual Summon are unique in that monsters from the hand can be used too, when appropriate. However, similar to the Fusion Summon, Tributes made for a Ritual Summon are not done until the Ritual Spell is successfully activated and carried out.
That covers just about everything you'll need to know when it comes to Summoning a Monster!
 Spells and Traps
Your cards with Green borders are Spells. You can use as many of these as you like during your own Main Phase. As mentioned earlier, these can be Activated or Set.
To activate a Spell, say you're doing so, and place it face-up in one of your Spell & Trap Card Zones (there are 5 of these, much like there are Monster Card Zones). You should pay any costs and select any targets for the effect now, if necessary, before either player can do anything else. If nothing else happens, you resolve the effect of that Spell card by following its instructions, then place the used Spell in the Graveyard.
To Set a Spell, just place it face-down in one of your Spell & Trap Card Zones. It is placed vertically, much like you would if you were simply activating it. A Set Spell card can be Activated from its face-down position by flipping it face-up, including during the turn you Set it.
Spells come in many varieties.
Normal Spells have no special properties.
Ritual Spells can be recognized by their symbol that looks like fire. Ritual Spells are used to Ritual Summon a monster, as mentioned earlier.
Quick-Play Spells feature a lightning bolt, denoting their quicker speed. These can be activated at any time during your own turn, even outside your main phase, and you can even use them straight from your hand! If you Set them, Quick-Play Spells can be used on your opponent's turn too, kind of like a Trap card, and similarly, you cannot activate a Quick-Play Spell the turn you set it.
Equip Spells have a symbol resembling a cross. To activate one, you must choose a face-up monster on the field (even under your opponent's control) that will be receiving the effect of the card (equipping it). Equip Spells remain on the field as long as the equipped monster is face-up on the field. Destroy (a specific kind of sending to the Graveyard) the Equip Spell as soon as the equipped monster is no longer face-up on the field. You can Equip any number of Equip Cards to a monster, so feel free to pile them on for more benefits.
Continuous Spells have an infinity symbol and also remain on the field once used, granting their effects as long as they are present.
Field Spells remain on the field too and sport a compass-like symbol. However, they are placed in their own Zone - the Field Card Zone. While a Field Spell is active (face-up), it will alter game play in some fashion, either by changing rules or the abilities of monsters. A face-down Field Spell doesn't do anything. Note that only one Field Spell can be active at a time. If a new Field Spell is activated and resolves, the old active Field Spell is destroyed. Your current Field Spell must be destroyed in order to play another Field Spell from your hand, even if your current Field Spell is face-down, since you only have 1 Field Card Zone of your own.
That covers the Spells!
Your cards with Pink borders are Traps. Traps must be Set for a turn before they can be Activated, being placed in an empty Spell & Trap Card Zone in the mean time. Activating a Trap card is more or less the same as activating a Spell, but it can be done during either player's turn as long as the Trap has been set since the previous turn. Declare that you're activating the Trap in question, flip it face-up, perform the actions written in its text, then send the Trap to the Graveyard. Notice that most Traps have specific activation timings. Others can be activated whenever you see fit.
Traps also come in multiple varieties.
Normal Traps have no special properties.
Continuous Traps have the same infinity symbol you see on Continuous Spells. Like their Spell brethren, Continuous Traps remain on the field to grant their effects as long as they remain face-up.
Counter Traps can be recognized by their backwards arrow. Counter Traps respond to specific events, nullifying them altogether or even redirecting card effects elsewhere. Only Counter Traps can respond to other Counter Traps, as nothing else matches their speed.
And with that, you're set on Traps!
 Monster Effects and Battle Positions
You'll find yourself using the effects of your Monsters as well as changing the Battle Positions of your monsters during the Main Phase quite often.
If a Monster you on your side of the field (or even in your hand!) has an effect you want to Activate, say so, and follow the instructions if neither player has a response.
If a Monster on your side of the field has not been Summoned this turn, has not declared an attack this turn, and has not already changed Battle Positions manually this turn, you can change that Monster's battle position. A monster in Attack Position is changed to Defense Position, and a monster in Defense Position is changed to Attack Position. If a monster is in face-down Defense Position, changing it to face-up Attack Position is called a Flip Summon. You can perform any number of Flip Summons during your Main Phase, but remember, only one manual position change per monster per turn!
 Loose Ends
You can do all the above actions in any order you so choose, even skipping the actions you can't or don't wish to make. When you're done making your moves, proceed to the Battle Phase or End Phase after confirming which with your opponent.
 More About the Battle Phase
The Battle Phase is generally short-lived and full of conflict. Here, you can declare attacks with your monsters if it is your turn. To declare an attack, choose one of your monsters in Attack Position (a monster in Defense Position cannot attack) that has not attacked this turn, as well as one of your opponents monsters to target with the attack. How the battle goes depends on the positions of the monsters.
Attack Position vs. Attack Position: The monster with greater ATK wins the battle. The monster with lesser ATK is destroyed and sent to the Graveyard after its controller takes damage equal to the difference in the ATK of the battling monsters. For example, if Player A's attacking monster has 1900 ATK and Player B's monster has 1500 ATK, Player B will lose 400 Life Points.
If the monsters on question have equal ATK, both are destroyed and sent to their respective Graveyards.
Monsters with 0 ATK are exempt from the above rule; since they have no power at all, they cannot destroy anything in battle, even each other.
Attack Position vs. Defense Position: In this battle, the ATK of the attacking monster is compared against the defending monster's DEF. If the Defense Position monster is face-down, flip it face-up so both players can see what it is.
If the ATK of the attacking monster is greater than the defending monster's DEF, the defending monster is destroyed and sent to the Graveyard. Unlike the battle between monsters in ATK position, the player who controlled the losing defender does not take any damage.
If the ATK of the attacking monster is equal to the DEF of the defending monster, neither monster is destroyed and no damage is dealt.
If the ATK of the attacking monster is less than the DEF of the defending monster, neither monster is destroyed and the controller of the attacking monster takes damage equal to the difference between the ATK and DEF of the monsters. If player A's monster with 1900 ATK attacks player B's monster with 2000 DEF, player A takes 100 damage to their Life Points.
It's possible that a face-down monster that was attacked had a FLIP: effect. Activate and resolve that FLIP: effect after determining whether that monster will be destroyed by the battle or not but before that monster is sent to the Graveyard. The FLIP: effect monster cannot affect itself with its effect if it was destroyed by the battle.
No Monsters on the Opposing Field: If your opponent doesn't have any monsters, you skip selecting an attack target and go straight into a Direct Attack on your opponent. Your opponent takes damage equal to the full ATK of your monster.
What if I attacked a monster, but it left the field before my attack reached it?: When a potential attack target appears or disappears during the battle step (the point where you're declaring your attacks), a replay occurs. You may choose to reselect the attack target of the current monster, and continue the attack. Whether you do this or choose to not attack anymore, the monster is treated as having declared an attack and cannot attack again this turn.
After resolving the battle, you can attack with another one of your monsters. Attacks are performed and resolved like this one at a time, and a monster does not need to attack if you don't want it to. If you're done with battling, proceed to Main Phase 2 after saying so.
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