Game mechanics Game mechanics refer to any action that automatically happens due to the interior workings of the Yu - Gi - Oh ! game . They are not treated as effects and most of the time cannot be avoided . Names . Every card has a specific name , but even something as simple as a name has rules attached to it . The basic rule is that each deck may only contain up to 3 cards of the same name . However , there are some cards with effects that change their name , like the Harpies . " Cyber Harpie Lady , " " Harpie Lady 1 , " " Harpie Lady 2 , " and " Harpie Lady 3 " all have the condition " " ( This card ' s name is always treated as " Harpie Lady " . ) " " This means a Deck can only contain up to 3 copies of cards that are named or always treated as " Harpie Lady " ( in any combination ) . Cards that change their name only at certain times such as " The Lady in Wight " or " Harpie Queen " are different and are not held by the same restriction . If only the name of a card is considered to be on the field , the effects of that card are not applied . For example , if " Gravekeeper ' s Priestess " is on the field , " Necrovalley " is considered to be on the field in the Field Spell Card Zone , so you can activate cards that require " Necrovalley " to be on the field , such as " Royal Tribute . " However , none of the effects printed on " Necrovalley " are applied , as the physical card is not on the field ; therefore , " Chaos Sorcerer " can still be Special Summoned from the hand because " Necrovalley " ' s ability to prevent cards in the Graveyard from being banish ed is not applied . Most cards have their names changed from the OCG to the TCG for one reason or another . Though normally harmless , it sometimes causes confusion or problems between archetypes ; these card are often renamed ( such as " Oscillo Hero # 2 " was to " Wattkid " ) or given an archetype condition to clarify this . Token Monsters . Many cards have the effect of creating Tokens for the field . Every Token Monster ' s original ATK , DEF , Level , Attribute , and Type are as they are listed on the card that summoned them . They can also have effects , but while they are considered written on the Token Monster itself , they are always considered Normal Monster s . Token Monsters have a few rules specifically for them : As long as the card that summoned them allows it , Token Monsters can be used as Tributes for Tribute or Ritual Summon s , or as Synchro or Fusion Material Monster s . However , if a card requires the Tributed monster to go to a certain zone outside the field , like the Graveyard or Banished Zone , Token Monsters cannot be used . Using Cards and the Graveyard . Whenever a card is destroyed or discard ed , when a Normal or Quick - Play Spell is used , or when a Normal or Counter Trap is used , it is always sent to the Graveyard unless a card effect states otherwise , such as " Macro Cosmos " or " Masked HERO Dark Law " . Field Spell Cards . Each player can have only one Field Spell Card on his or her side of the field at a time . A player who controls a Field Spell Card may play a new one by sending their current one to the Graveyard ( this is not considered destroying it ) . This creates a minor gap of time in which there is no Field Spell Card on the field , a large enough gap to destroy cards that cannot survive without the presence of one , such as " Earthbound Immortal " and " Malefic " monsters . Before the 2014 rule change , only one Field Spell Card could be on the field at a time . If a player had one on the field and the other player activated a second one , when the second one ' s activation resolved , the first one was automatically destroyed . Because this was a Game Mechanic and not a card effect , cards like " Magical Citadel of Endymion " were not protected from this destruction . However , if the second Field Spell Card was destroyed before its activation resolves , such as with " Mystical Space Typhoon " , the original one was not destroyed . Equip Cards . Equip cards continuously target the equipped monster to make sure it is still there . If that monster is no longer face - up on the field , the Equip card is automatically destroyed . This can be due to either being destroyed or removed from the field by battle of card effect , or simply being flipped face - down with " Book of Moon " . Additionally , Equip cards also continuously target to make sure the equipped monster fits its requirements , and if it suddenly no longer meets its requirements , the Equip card is destroyed . Fusion Substitutes . There are multiple cards with the following effect : " " You can substitute this card for any 1 Fusion Material Monster . When you do this , the other Fusion Material Monster ( s ) must be the correct one ( s ) . " " While these are great cards for Fusion Summon ing , there are other limits to their effects that aren ' t listed : Pendulum monsters . Whenever a Pendulum monster on the field in either a Monster Zone or a Pendulum Zone would be sent to the Graveyard , it is placed in the Extra Deck , face - up . While there , it is treated as an additional card on the Extra Deck , rather than a card in a card zone , so it cannot be targeted by card effects . Infinite Loops . Within the TCG there are cards that , when combined together , create loops that can ( and just might ) never end . As such , a rule has been put in place for both types of infinite loop . First is the No Net Change loop . This type of loop is one where the card effects continue to loop around in a circle without any real changes or control of whether they happen or not . Players may not activate or summon a card if they know it would create a No Net Change loop . If this has been done by accident , play rewinds to the point of the offending activation or summon and continues from there . Additionally , there are Net Change loops are those that also loop endlessly without any control , but a change is being applied with each loop that causes a player to become closer to losing the game , such as a loss of Life Points or the number of cards in a player ' s deck being reduced . Loops such as these are legal and are allowed to loop endlessly until the change stops happening , in which the card causing the loop will be automatically destroyed at the end of a loop . A loop where the only Net Change is the increase of a player ' s Life Points is considered a No Net Change , because a game cannot be ended due to a player having too many Life Points . All other loops , such as the Quillbolt Loop , are controlled by a player and can be stopped at anytime when the player sees fit . Such loops are completely legal , but if it becomes a controlled No Net Change loop , the player cannot perform it ; this would be a form of stalling and is not legal . An example would be a player using a Burn Quillbolt Loop when the opponent has activated " Hallowed Life Barrier " for the turn .