A field-unique card is a card that has a condition that prevents more than 1 card being on the field with its name.
- This means that if a field-unique card is face-up on any player's field, and a new one is placed on the field face-up or flipped face-up, then all new copies are sent to the Graveyard by game mechanics instead. Furthermore, if there is already a field-unique card face-up on the field, another card with the same name cannot be Summoned face-up (even if the Summon would cause the copy already on the field to be removed).
- Additional copies can exist face-down (so they can be Set/Special Summoned face-down), but as soon as they are flipped face-up the restriction applies and sends them to the Graveyard. Furthermore, they cannot be Flip Summoned if another copy is already face-up on the field.
- If another copy of a face-up field-unique monster is attempted to be Summoned from Graveyard or Banished Zone, such by the effect of "Return from the Different Dimension", then all illegal Summons will simply fail at resolution.
All "Earthbound Immortal" and most "Malefic" monsters are field-unique with other cards of that same archetype.
OCG/TCG "Field-Unique" cards
Anime "Field-Unique" cards
All "Field-Unique" cards
- Side-Unique cards are essentially the same rule as Field-Unique, except that they apply only to a single player's field. ie: Both players can have the same card on their field without either being destroyed as a State-Based Action; however a given player may still only have one on their field, treated the same way as Field-Unique.