Demystifying Rulings, Part 11: Move Legality

In this article, we use the language of ‘attempts’ to study various rulings regarding when actions and activations are legal.

Don’t forget to check out the last article on Negation:

Can Fossil Dyna Pachycephalo be used for an Xyz Summon?
Fossil Dyna Pachycephalo’s effect (of interest) reads as follows:
Neither player can Special Summon monsters.

If we read it as “Neither player can ‘attempt to’ Special Summon monsters” then it becomes clear why you cannot use Fossil Dyna for a Synchro or Xyz Summon, or as a Tribute for a Special Summon – even though that those actions would remove Fossil Dyna from the field, you can’t even attempt them while Fossil Dyna is face-up.

If a Special Summon is negated, can Pot of Duality be activated afterwards?
Duality has this clause:
You cannot Special Summon during the turn you activate this card.

The important factor here is whether a Special Summon was actually successful or not. Duality cannot be activated if a Special Summon was successful that turn.

For Special Summons that do not occur while a Chain is resolving, if the Special Summon is negated, the Special Summon was not successful. So for example, if an Xyz Summon is negated by Solemn Warning, Pot of Duality can be used later in the turn.

For Special Summons that occur during a resolving Chain, if the activation of the effect or the effect itself is negated, then the Special Summon was also not successful.

For example, suppose the effect of Summoner Monk activates:
Once per turn: You can discard 1 Spell Card; Special Summon 1 Level 4 monster from your Deck, but that monster cannot attack this turn.

If Solemn Warning negates the activation of Summoner Monk, then Duality could be activated afterwards. Also, if Effect Veiler was used to just negate the effect, Duality could be activated afterwards.

Gozen Match/ Rivalry of Warlords
Gozen Match reads as follows:
Each player can only control 1 Attribute of monster. Send all other face-up monsters they control to the Graveyard.

Rivalry is the same, but for Type.

Similar to Fossil Dyna Pachycephalo’s case, you cannot attempt to Xyz Summon, say, an EARTH monster using your two DARK monsters. That would be a direct attempt to control a different Attribute of monster.

There are several other rulings that are easier to understand by thinking in this way. The following is Konami’s article on these cards:

Principle of Costs
Let’s get straight to the principle of costs: “If you can’t pay the cost, you can’t activate the effect”.

Often, a card like Masked HERO Dark Law is to blame:
Any card sent to your opponent’s Graveyard is banished instead.

While Dark Law is face-up on your opponent’s side of the field, there’s no way to successfully send a card from your hand to the Graveyard.

Now let’s look at Effect Veiler:
During your opponent’s Main Phase: You can send this card from your hand to the Graveyard, then target 1 face-up Effect Monster your opponent controls; negate that opponent’s face-up monster’s effects until the end of this turn (this is a Quick Effect).

Effect Veiler’s cost is sending it to the Graveyard, but while Dark Law is face-up, if you were to try to send Veiler to the Graveyard, it would never get there. You can’t pay the cost of Veiler, so you can’t activate the effect at all.

If the card doesn’t specifically need to be sent to the Graveyard (eg. if it just needs to be Tributed or discarded) then its effect can still be activated.

Principle of Mandatory Effects
The mandatory effects principle is: “Mandatory effects always activate, unless explicitly prevented”. For example, the effect of Sangan to search the Deck when it is destroyed would still activate when Thunder King Rai-Oh destroys it by battle.
When this card is sent from the field to the Graveyard: Add 1 monster with 1500 or less ATK from your Deck to your hand.

Neither player can add cards from their Deck to their hand except by drawing them.

Of course, as long as Rai-Oh is face-up at resolution, Sangan’s effect will resolve without adding a card.

However, if Majesty’s Fiend is face-up, Sangan’s effect would not activate at all:
Monster effects cannot be activated.

Discarding and Special Summoning the discard with Lumina, Lightsworn Summoner
A common question is whether this effect can be used to discard a Level 4 or lower Lightsworn monster, and then Special Summon the same monster.

Lumina’s effect in question reads as follows:
Once per turn: You can discard 1 card, then target 1 Level 4 or lower “Lightsworn” monster in your Graveyard; Special Summon that target.

Now, if your Graveyard is empty (of Lightsworn monsters), you cannot attempt to activate the effect at all, even if you promise to discard a Lightsworn monster. The game doesn’t allow you to do it.

However, if you do have a Lightsworn monster in the Graveyard already, then you CAN do it. The activation is legal, so you can discard a Lightsworn monster, and since you ‘then’ pick a target, you can target the discarded monster at this point.

More Rulings
This section is for a variety of miscellaneous rulings to do with activation legality. By studying them, we can start to build an understanding of when we can and cannot activate things.

Here are some rulings about things you can’t do:

-You CANNOT activate Bottomless Trap Hole while Imperial Iron Wall is already face-up.
This is because you cannot attempt to banish while Imperial Iron Wall is out.

Note that the conjunction on BTH (‘and if you do’, in this case) is not relevant here. Conjunctions tell us how to resolve effects, and nothing about activation legality.

-You CANNOT activate Mind Crush if you don’t have a card in your hand, even if you ‘know’ you’re going to declare the right card.
This is because, if your opponent’s hand happened to not have the cards at resolution, you wouldn’t be able to attempt to discard anything.

-You CANNOT activate Dark Hole if the field is empty
This is because you wouldn’t have anything to attempt to destroy.

Now here are some rulings which tell us what we can do:

-You CAN activate the effects of monsters (and pay the cost to activate the effects) while their effects are being negated by Skill Drain or Effect Veiler.
This ruling is telling us that even though you know their effects will be negated at resolution, you can still attempt to activate their effects (this was mentioned in the last article).

-You CAN activate the effect of Divine Wrath to negate the effect of a monster in the Graveyard.
This ruling is telling us that even though you cannot destroy cards in the Graveyard, you can still attempt to do it.

-You CAN activate Bottomless Trap Hole on Beelze, King of the Diabolic Dragons.
This ruling is telling us that even though a card cannot be destroyed, you can still attempt to destroy it.

-You CAN activate Bottomless Trap Hole on Apoqliphort Towers.
Similar to the above ruling, this one is telling us that even though a card is unaffected by Trap effects, you can still attempt to use Traps on it.

-You CAN activate Foolish Burial to while Macro Cosmos is face-up.
This ruling is telling us that while all cards are being banished instead of being sent to the Graveyard, you can still attempt to send cards to the Graveyard as part of an effect. But recall from the principle of costs that you cannot try to do so to pay a cost.


There is more to move legality that we’re not going to go into here, and it can get quite hairy if you venture past the cases we’ve covered. For more complicated cases, it’s best to consult an article or check the rulings case by case.

Quiz time!
Use the above rulings to answer the following questions. If you aren’t sure about any of the answers, scroll back up to find the ruling that is most relevant to the situation.

(1) Which of the following monsters’ effects can be activated while Macro Cosmos is face-up?

-Artifact Lancea
During your opponent’s turn: You can Tribute this card from your hand or face-up from your side of the field; neither player can banish cards for the rest of this turn (this is a Quick Effect).

-This effect of Nekroz of Valkyrus
When an opponent’s monster declares an attack: You can banish 1 “Nekroz” card from your Graveyard and discard this card; negate the attack, then end the Battle Phase.

-The effect of Harpie Queen
You can discard this card to the Graveyard; add 1 “Harpies’ Hunting Ground” from your Deck to your hand.

-The effect of Maxx “C”
During either player’s turn: You can send this card from your hand to the Graveyard; this turn, each time your opponent Special Summons a monster(s), immediately draw 1 card.

(2) Which of the following ways to Xyz Summon Number 39: Utopia are legal?

-Using 2 Numeral Hunter
Neither player can Special Summon “Number” Xyz Monsters.

-Using 2 Beast-Types with Rivalry of Warlords face-up
Each player can only control 1 Type of monster.

-Xyz Summoning after the activation of Cardcar D’s effect was negated by Divine Wrath.
During your Main Phase 1, if this card was Normal Summoned this turn: You can Tribute this card; draw 2 cards, then it becomes the End Phase of this turn. You cannot Special Summon during the turn you activate this effect.

(3) Which of the following effects can/will be activated while Koa’ki Meiru Drago is face-up? (Assume the player only has LIGHT and DARK monsters in their Graveyard).
Neither player can Special Summon LIGHT or DARK monsters.

-This effect of Light and Darkness Dragon
When this card is destroyed and sent to the Graveyard: Target 1 monster in your Graveyard (if possible); destroy all cards you control, also Special Summon that monster (if any).

-Book of Life
Target 1 Zombie-Type monster in your Graveyard and 1 monster in your opponent’s Graveyard; Special Summon the first target, also banish the second target.

-Faustian Bargain on Koa’ki Meiru Drago (with only LIGHT and DARK monsters in hand)
Send 1 Special Summoned monster on either side of the field to the Graveyard and Special Summon 1 Level 4 or lower Normal Monster from your hand.

(4) In which of the following circumstances can you activate Stellarnova Alpha?
When a Spell/Trap Card, or monster effect, is activated: Send 1 face-up “tellarknight” monster you control to the Graveyard; negate the activation, and if you do, destroy that card, then draw 1 card.

-To negate the effect of Necro Gardna in the Graveyard
During your opponent’s turn: You can banish this card from your Graveyard; negate the next attack this turn from a monster your opponent controls (this is a Quick Effect).

-While your opponent controls Protector of the Sanctuary
Your opponent cannot draw cards except during Draw Phases.

-To negate the effect of Evolzar Solda (with 2 Xyz Materials)
This card cannot be destroyed by card effects while it has Xyz Material. When your opponent Special Summons a monster(s): You can detach 1 Xyz Material from this card; destroy that monster(s).

-While Royal Decree is face-up
Negate all other Trap Card effects on the field.

-To negate the effect of Ryko, Lightsworn Hunter flipped face-up during the Damage Step
FLIP: Apply these effects in sequence.
-You can target 1 card on the field; destroy that target.
-Send the top 3 cards of your Deck to the Graveyard.



(1) The effects of Artifact Lancea and Nekroz of Valkyrus
Lancea and Valkyrus only need to be Tributed and discarded respectively, so their effects can be legally activated, whereas Harpie Queen and Maxx specify the Graveyard, so their effects cannot, under the principle of costs.

(2) Xyz Summoning after the activation of Cardcar D’s effect was negated by Divine Wrath.
Numeral Hunter and Rivalry of Warlords block even any attempts to Special Summon a Number or non-Beast-Type respectively. Since the activation of Cardcar’s effect was negated, it’s like it never happened, so the condition preventing Special Summoning doesn’t apply (recall this from the last article).

(3) The effect of Light and Darkness Dragon
LaDD’s effect is mandatory, so must activate by the principle of mandatory effects. Book of Life and Faustian Bargain both attempt to Special Summon, so could not be activated. Note that Book of Life’s ‘also’ conjunction, as well as the fact that Faustian Bargain would send Drago to the Graveyard, are both irrelevant for determining activation legality in this case.

(4) Each case except for while Protector is face-up
Alpha can still be activated and attempt to destroy Necro Gardna in the Graveyard (as with Divine Wrath) as well as Solda (as with Beelze and Bottomless). It can also be activated under Decree, even though its effect would be negated (as with monster effects under Skill Drain and Effect Veiler). Recall finally from earlier articles that Alpha can be activated during the Damage Step, by virtue of being a Counter Trap.

However, when Protector is face-up, you cannot attempt to draw for Alpha, so you cannot activate it.

The final article is upon us!
It will cover the game state, verifications, and… one mystery topic. What will it be? Find out on Sunday!

Don’t miss it!

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