Sometimes an optional effect can only be activated "when" a condition happens. In this case, you are only allowed to activate the effect when the activation condition being met was the last thing to happen in the game. If something else happened after the activation condition was met, then you have missed the timing (タイミングを逃す Taimingu wo Nogasu), and cannot activate the optional effect, unless it is a certain type of optional Trigger Effect, such as ones phrased "If... you can...". Optional effects which can miss the timing are phrased "When... you can..."
This mainly applies to Monster Cards with optional Trigger Effects such as "Peten the Dark Clown" and "Poison Draw Frog", but it can also affect Spell and Trap Cards such as "Appropriate" and "Heart of the Underdog".
For example, consider the following rulings:
- If "Peten the Dark Clown" is Tributed for a Tribute Summon, the last thing that happened was that a monster was Summoned, so the effect of "Peten" does not activate.
This is because you first Tribute "Peten the Dark Clown" as a cost, and afterwards the other monster is successfully Tribute Summoned. The last thing to happen was not "Peten the Dark Clown" being sent to the Graveyard, so it misses the timing.
- If "Peten the Dark Clown" is Tributed for "Mystik Wok" or "Cannon Soldier", the last thing that happened was that those effects resolved, so the effect of "Peten" does not activate.
This is because you first Tribute "Peten the Dark Clown" as a cost, and afterwards "Mystik Wok" resolves and increases your Life Points. The last thing to happen was not "Peten the Dark Clown" being Tributed, so "Peten the Dark Clown" misses the timing.
- "Appropriate" can only be activated if the last effect on the Chain ends with your opponent drawing a card(s) outside of their Draw Phase....
- Your opponent cannot activate "Appropriate" after you activate "Graceful Charity" since the last effect that resolves with "Graceful Charity" is discarding, not drawing, and your opponent misses the timing. However, if your opponent already controls an active "Appropriate" and you activate "Graceful Charity", then your opponent may draw 2 cards.
As explained, the last thing to occur is not drawing, so "Appropriate" misses the timing.
Versus new activations
Activating new effects will not cause an effect to miss the timing. Even if you activate a new card, then it is still considered to be "When..." the activation condition is correct.
- Missing the timing: Suppose you have 3 copies of "Heart of the Underdog" on the field, and draw a Normal Monster Card during your Draw Phase. You can activate the effects of all 3 copies of "Heart of the Underdog" immediately, and because they activate simultaneously, they form a Chain with Chain Links 1, 2, and 3. If you draw a Normal Monster Card for Chain Link 3 or Chain Link 2, your copies of "Heart of the Underdog" do not activate again. This is because they are "when... you can" optional Trigger Effects, and you "miss the timing" because you drew the Normal Monster Card during a chain and not as Chain Link 1. However, if you draw a Normal Monster Card for Chain Link 1, all 3 copies of "Heart of the Underdog" will activate their effects again.
Note that all three copies of "Heart of the Underdog" will still activate. After you activate the first copy of "Heart of the Underdog", then last thing to happen is you drawing a Normal Monster (you do not consider the activation of the first copy's effect), so you can activate the second copy.
- When "The Wicked Avatar" is Tribute Summoned, its effect begins a chain. You can chain "Bottomless Trap Hole" or "Torrential Tribute" to this effect.
"Bottomless Trap Hole" can still be activated because it is still considered to be "When "The Wicked Avatar" was successfully Summoned". It does not matter that the effect of "The Wicked Avatar" already activated as Chain Link 1.
Versus "and", "and if you do", "also" & "then" conjunctions
With cards with Problem Solving Card Text that state in their effect a "then", followed by another part of the effect, will cause cards that have an activation condition "when... you can" something happens to miss the timing to activate the effects. This is because the different parts of the effects are NOT considered to happen simultaneously, but rather you do the part before "then", and then you do the part after "then".
- Player A controls Bujin Yamato and has Bujin Mikazuchi in their hand and Player B has Soul Taker in their hand. Player B activates Soul Taker, targeting Bujin Yamato. Soul Taker states: "Target 1 face-up monster your opponent controls; destroy that target, then your opponent gains 1000 Life Points." Bujin Mikazuchi states: "When a Beast-Warrior-Type "Bujin" monster you control is destroyed by battle or by card effect and sent to the Graveyard: You can Special Summon this card from your hand." Player A's Bujin Mikazuchi will miss the timing here, since destroying is the first thing to happen, THEN gaining Life Points happens, which is because destroying and gaining Life Points do not happen simultaneously.
Cards that state "and", "and if you do" or "also" do not miss the timing if the last thing to happen is one of the above in the text, and this is because these effects ARE considered to happen simultaneously, unlike "then", and therefore cards that activate do not cause any timing issues.
- Player A controls Number 61: Volcasaurus and Player B control Bujin Yamato and has Bujin Mikazuchi in their hand. Player A activates Number 61: Volcasaurus' effect targeting Bujin Yamato. Number 61: Volcasarus states: "Once per turn: You can detach 1 Xyz Material from this card to target 1 face-up monster your opponent controls; destroy that opponent's monster, and if you do, inflict damage to your opponent equal to the destroyed monster's original ATK." Bujin Mikazuchi states: ""When a Beast-Warrior-Type "Bujin" monster you control is destroyed by battle or by card effect and sent to the Graveyard: You can Special Summon this card from your hand." Since destroying and inflicting damage happen simultaneously, Bujin Mikazuchi can Special Summon itself from the hand. The same results would happen in the case of "and" or "also", but not "then".
Optional effects that do not miss the timing
Note that Missing the timing only applies to optional effect that are activated "When... you can..." something happens. It does not apply to optional effect that are activated "If..." something happens, such as "Watapon" or "Ultimate Ancient Gear Golem", and it does not apply to optional effects that are activated "After..." something happens (like "Voltanis the Adjudicator"). Effects like these can never miss the timing. Similarly-phrased "When..." compulsory effects also cannot miss the timing.
Examples of Missing the timing:
- Card Rulings:Butterfly Dagger - Elma
- Card Rulings:Dark Magician of Chaos
- Card Rulings:Heart of the Underdog
- Card Rulings:Peten the Dark Clown
- Card Rulings:Pinch Hopper
- Card Rulings:Geargiaccelerator
Examples of effect that cannot miss the timing:
Official Print Regarding Missing the timing: