| Once per turn
|Japanese (base text)||
1 Tān ni 1 Do
once per turn
"Once per turn effects" are a kind of card effect. There are three kinds of "Once per turn effects".
The first is typically referred to as a "Once per turn effect". The second is typically referred to as a "Only once per turn effect". The third is typically referred to as an "Additional Normal Summon once per turn effect".
Once per turn effects
These kinds of effects can be seen by the fact that the effect starts with "once per turn" and possibly another Activation Requirement as well.
- Once per turn: You can detach 1 Xyz Material from this card, then target 1 Defense Position monster on the field; change it to face-up Attack Position, and if you do, it loses 600 ATK.
Typically, these kinds of effects are either Ignition Effects or Quick Effects, but they can also be Trigger Effects. These kinds of effects can only be used once per turn as long as that specific card stays face-up on the field. For example, if "Photon Papilloperative" activates its effect, and then is later destroyed that turn, and "Xyz Reborn" is used to Special Summon it back from the Graveyard, then you can once again use the effect as it has left the field, which "resets" the once per turn condition, thereby allowing it to activate once again. This principle also applies for Spell and Trap Cards. If you control multiple of the same card, you can activate both of their effects as well.
Only once per turn effects
These kinds of effects can be seen by the fact effect has either "You can only activate 1 "X" per turn" or "You can only activate/use the/this effect of "X" once per turn." Cards stating "once per Duel" instead work in the same way (they just apply for the entire Duel instead).
- Add 1 "Spellbook" card from your Deck to your hand, except "Spellbook of Secrets". You can only activate 1 "Spellbook of Secrets" per turn.
- 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.
Like with "once per turn effects", these can be Ignition Effects, Quick Effects or Trigger Effects; however, unlike them, these effects can only be used once per turn, regardless of them being reset, or you having multiple copies. This means you cannot activate multiple copies of "Spellbook of Secrets", since it states you can only activate one of them per turn.
If the activation of a card that states "You can only activate this effect of "card name" once per turn" is negated, then this means you can activate it once again. However, 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.
This kind of condition is not affected by cards' names being changed on the field. 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.
You can only gain this effect once per turn
Unlike the other "Once per turn" effects, these work a bit differently. These can be identified by the text "(You can only gain this effect once per turn.)". Most such effects allow the player to perform an additional Normal Summon/Set that turn without starting a Chain, but only one of these effects can be gained per turn. Even if the player controls both "Evilswarm Castor" and "Fire Formation - Tensu", the player still can only gain the effect of one to perform an extra Normal Summon.
- "During the turn this card was Normal Summoned, you can Normal Summon 1 "lswarm" monster in addition to your Normal Summon/Set. (You can only gain this effect once per turn.)"
Cards and effects that start a Chain, then perform the Normal Summon immediately after resolving (such as "Pahunder" and "Ultimate Offering") as well as cards and effects that change the maximum number of Normal Summon/Sets that turn (such as "Double Summon" and "Chain Summoning") can still be used, regardless of if an effect that specifies "(You can only gain this effect once per turn.)" was used that turn.
- ↑ Konami. Yu-Gi-Oh! Official Card Game - Perfect Rulebook 2015. p. 47. https://ygorganization.com/perfectrulebook/.