Once per turn

Once per turn
Japanese	１ターンに１度（ど）
Japanese (ruby)	１ターンに１ど
Japanese (base text)	１ターンに１度
Japanese (romanized)	Ichi Tān ni 1 Do
English	once per turn
Other names French: une fois par tour German: einmal pro Spielzug Italian: una volta per turno Korean: 1턴에 1번 (1 Turn ? 1 番) 1 Teon-e 1 Beon Portuguese: uma vez por turno Spanish: una vez por turno Traditional Chinese: 每回合1次 Měi Huíhé 1 Cì / Mui5 Wui4 hap6 1 Ci3 Formerly: 每1回合1次 Měi 1 Huíhé 1 Cì / Mui5 1 Wui4 hap6 1 Ci3

Some cards and effects can only be activated once per turn. There are three distinct ways in which this limitation is commonly applied.

"Once per turn"

"Barrel Dragon"

"Once per turn" effects can be identified by the text "once per turn" in their activation conditions.

These kinds of effects can only be used once per turn per card, while that card is face-up in its current location. (Even if that effect's activation is negated, it cannot be activated again that turn.) This restriction only applies to that copy of the card; if a player is in possession of multiple cards with the same name that have the same "Once per turn" effect, they can activate each one during that turn. Additionally, if a card that activated its "Once per turn" effect leaves its current location (the entire field is considered the same location) or is flipped face-down, its effect can be activated again during that same turn.

For example, if "Barrel Dragon" activates its effect, it cannot activate its effect again that turn while it remains face-up on the field. However, if after activating its effect it is destroyed and sent to the Graveyard, then Special Summoned from the Graveyard by "Call of the Haunted", it can then activate its effect again during that turn. Similarly, if a player controls two copies of "Barrel Dragon", they can activate the effects of both during the same turn.

A small number of cards have non-activated Continuous Effects that also have a once per turn clause (e.g. "ZW - Pegasus Twin Saber"). In their cases, they can only each apply their effects once per turn, without activating.

An exception to the above rules are monsters that specifically change themselves to face-down Defense Position (such as "Swarm of Locusts" and "Flip Flop Frog"): the same card cannot activate such an effect again for that turn after the next time it is flipped face-up. However, multiple copies can still use the effect once each, also if one such card leaves the field and then returns, or if it is flipped face-down by another card's effect then flipped face-up once again, the effect will still reset.

"Only once per turn"

Main article: Only once per turn

"Spellbook of Secrets"

"Only once per turn" effects can be identified by one of the following conditions: "You can only activate 1 "X" per turn" or "You can only activate/use [reference to effect] of "X" once per turn" (Japanese: このカード名の (Effect #) 効果は１ターンに１度しか使用（発動）できない。). Cards stating "once per Duel" instead of "once per turn" (Japanese: ・・・(Effect #) 効果は１デュエルに１度・・・) work in the same way, but apply for the entire Duel instead.

The reference to the effect is most often "the effect" or "this effect", but can also be other references such as "1 of these effects", "each of the preceding effects" etc. depending on the structure of the card's text.

If an effect has this condition, each player can only activate that effect of cards with the same name once per turn. This kind of condition is not affected by cards' names being changed; for example, if "Fairy Archer" activates its effect, even its name is changed by "Hero Mask" later that turn, it cannot activate its effect again that turn.

If a card states "You can only use this effect of (card name) once per turn", then even if the activation is negated, you cannot activate it once again. On the other hand, if a card states "You can only activate this effect of (card name) once per turn", that effect can be activated again that turn if its activation is negated.

Example 1 ("Spellbook of Secrets"): Add 1 "Spellbook" card from your Deck to your hand, except "Spellbook of Secrets". You can only activate 1 "Spellbook of Secrets" per turn.

If a player activates "Spellbook of Secrets" and its activation is not negated, this means that player cannot activate the card "Spellbook of Secrets" again during that turn. If a player activates it and its activation was negated, the player may activate another one during the same turn if they have another one.

Example 2 ("Bacon Saver"): During either player's Battle Step, while an attack is occurring: You can banish this card from your Graveyard; negate the attack. You can only use the effect of "Bacon Saver" once per Duel.

If a player activates the effect "Bacon Saver", this means that player cannot activate the effect of "Bacon Saver" again during that same Duel, even if the activation of the effect was negated.

Some cards apply a single limitation to multiple effects. In that case, if a player activated any of those effects, they cannot activate any of the other effects during the same turn.

Example 3 ("Fluffal Bear"): You can send this card from your hand to the Graveyard; Set 1 "Toy Vendor" directly from your Deck to your Spell & Trap Zone. You can Tribute this card, then target 1 "Polymerization" in your Graveyard; add it to your hand. You can only use 1 "Fluffal Bear" effect per turn, and only once that turn.

If a player activates either effect of "Fluffal Bear", they cannot activate that effect again, or the other effect, during that same turn.

"You can only gain this effect once per turn"

Main article: Gain this effect once per turn

"Constellar Pollux"

These effects can be identified by the text "(You can only gain this effect once per turn.)".

Each player can only apply one effect with this text per turn, even if the cards have different names or different effects. For example, even if the player controls both "Evilswarm Castor" and "Fire Formation - Tensu", the player can only gain the effect of one to perform an extra Normal Summon.

Most effects with this text allow the player to perform an additional Normal Summon/Set that turn without starting a Chain. The only cards with this text that do not have such an effect are "Zefraath" (which grants an additional Pendulum Summon) and "Dice Re-Roll" (which allows a player to redo a dice roll).