Transformations

Double-faced cards that transform are a rather interesting kind of card that was introduced in the Innistrad set. Due to this unique peculiarity, they can also cause a bit of confusion sometimes due to how they work.

Many such cards have a triggered ability that transforms the card (when it's on the battlefield.) One of the most typical such ability is "at the beginning of each upkeep, if no spells were cast last turn, transform (this card)." Many players actually don't realize that this is a normal triggered ability that uses the stack, and therefore can be responded to. (This is because the ability starts with the word "at".) While it's not very usual for this to have any effect on anything, there are some cases where it does. A good example is Ulvenwald Mystics/Primordials.

If this card is on the "Primordials" side and its transform ability triggers, that ability can be responded to: The card's controller can activate its regereneration ability before the transform ability resolves. Therefore the permanent becomes Ulvenwald Mystics that has a regeneration shield.

Anyway, that was not really the reason why I wanted to write this article. Rather, I want to pose a problem: Suppose that there's an Afflicted Deserter on the battlefield, and it's going to transform (because no spells were cast last turn.)

 

If it transforms, its controller can destroy an artifact. As a response to the triggered ability, someone casts Snakeform targeting Afflicted Deserter. What happens?

(As a side note, it's useful to know that this is actually the earliest possible time in a turn that any player can do anything. The beginning phase consists of the untap, the upkeep, and the draw steps. No players get priority during the untap step, and any ability that triggers "at the beginning of upkeep" will trigger before any player gets priority. Therefore it's not possible to do anything to Afflicted Deserter during that turn before its ability triggers.)

To many players it can be unclear what exactly happens in this situation. Does Snakeform stop the transformation? Does it not stop it, but only affect the Afflicted Deserter side and not the Werewolf Ransacker side? Does it affect both sides? Is it perhaps a question of timestamps?

To understand exactly what's going on, we have to understand double-faced cards and what it means when they transform. The key point to understand is that transforming a double-faced card is, effectively, just changing its printed information. When it transforms it's not a new permanent, but the same one. It's effectively just as if its text and other information had been replaced with some other text.

Note that this is not an effect that uses layers. It's literally information that's printed on the card, and thus defines the card, even if this information changes when it transforms. Other effects, such as the one caused by Snakeform, will affect it on layers regardless of what the card text might be saying at any given moment.

(To be more precise, the "becomes a green Snake" is in effect on layer 4, the "loses all abilities" is in effect on layer 6, and the 1/1 power/toughness setting ability is in effect on layer 7b.)

So Snakeform will make it a 1/1 green Snake with no abilities regardless of whether it transforms or not.

So the remaining question is: Does it transform? The answer is yes: The transformation ability is already on the stack, and therefore is unaffected by whatever else may be affecting the card. When the ability resolves, it will transform the card as usual.

Therefore when all resolves, it will become a 1/1 green Snake named Werewolf Ransacker with no abilities. Thus it will not destroy any artifact (because at this point it has no such ability.)

When do things "target" in Magic the Gathering?

There's a quite unambiguous and overarching de-facto rule in Magic the Gathering that's surprisingly little-known among players, and it's that the only place in the entire game where anything "targets" is on the stack. This can be a bit surprising to many players.

Something targeting something else is a completely non-existent concept anywhere else than on the stack; only things on the stack can target. (Spells and abilities that contain the word "target" will target something when they are entering the stack, and when they resolve. However, they do not target anything anywhere else, nor in any other situation.)

While this isn't an actual explicit rule of the game, it's a de-facto rule (ie. it's just true because no game rule recognizes targeting as happening anywhere else than on the stack.)

This principle very seldom affects the game in practice, but when it does, it is often surprising for those who do not know this, usually causing confusion and protest.

One quintessential example would be aura enchantments: Auras are spells that target, but do so only when they go to the stack and resolve from there. If an aura enters the battlefield by means other than by being cast, it doesn't actually target. This can have surprising consequences.

Example: You attack with Sun Titan, and use its ability to return a Pacifism to the battlefield. You can then attach said aura to, for example, a Primal Huntbeast that your opponent controls, even though it has hexproof.

Most players who are unaware of this situation will protest and say that you can't enchant Primal Huntbeast, it has hexproof. However, when an aura enters the battlefield from anywhere else than the stack, it does not target and thus hexproof doesn't affect it. This can be, admittedly, rather unintuitive.

Moreover, since choosing to enchant Primal Huntbeast does not use the stack, it's something that cannot be responded to. As soon as Pacifism enters the battlefield, its controller chooses what it enchants and there's no time to respond to it. (Your opponent could respond to Sun Titan's triggered ability, but at that point he or she does not know what you will be attaching Pacifism to. You make the choice as Titan's ability resolves and Pacifism enters.)

(Technically speaking, there's a difference between an "Aura" and an "Aura spell." The former is a card, which becomes a permanent when on the battlefield. It does not target anything. The latter is technically speaking a different thing; it's more like a conceptual effect that goes to the stack and then resolves, and causes the Aura card to enter the battlefield attached to whatever the spell targeted. If the target becomes illegal, the spell fails to bring the Aura card to the battlefield, and it instead goes to the graveyard. Technically speaking the Aura card doesn't care what brings it to the battlefield: When it does, it enters attached to something. If the effect that brings it to the battlefield specifies what it enters attached to, it enchants that. If the effect did not specify, then the player chooses what it enchants.)

All permanents are creatures

There's a quite famous combination of two cards in Magic the Gathering which, if they are on the battlefield at the same time, make all permanents artifact creatures: Mycosynth Lattice and March of the Machines.

(As you may know, or if you have read my previous blog posts, an effect making something an artifact creature has an implicit "in addition to its other types" without the effect having to specifically state it. This means that all permanents retain their other types in addition to being artifact creatures.)

This combination not only causes all kinds of shenanigans, the least of which is most certainly not the fact that all lands die because of being creatures with 0/0 power/toughness (unless there's something else increasing their toughness), but it also allows many interesting interactions with non-creature permanents that are not normally possible (because most of the "interesting" interactions usually target creatures and nothing else.)

Just to mention one of the numerous possibilities, take for example the situation where Clone enters the battlefield as a copy of Garruk Relentless.

Under the current rules (as of writing this blog post) both of them would simply die as a state-based action due to the planeswalker uniqueness rule, so nothing special happens. However, with the soon upcoming Magic 2014 rules change the Clone can remain on the battlefield as a copy of Garruk. (If Clone was cast by an opponent, it just stays. If it was cast by Garruk's controller, he or she can choose which one stays and which one goes to the graveyard.)

(Note that as Clone enters the battlefield as a copy of Garruk, it will have 3 loyalty counters, because that's a property of the Garruk card.)

It was possible to have Clone remain on the battlefield even under the old rules, but it required a much more contrived set of circumstances. The new rules make it much simpler.

So Clone is now a copy of Garruk Relentless. What's so special about this? The special thing is that Garruk Relentless is a double-faced card, while Clone isn't. Clone only copies the "Garruk Relentless" side of the card. And one of the copied abilities is "When Garruk Relentless has two or fewer loyalty counters on him, transform him."

So, what happens if Clone, which is a copy of Garruk, has less than three loyalty counters? It still may not seem like much: The ability tries to transform the clone, but since it can't (because it's not a double-faced card), it just does nothing.

Most people would just leave it at that. However, technically speaking, that's not the end of the story. What really happens is that when the clone's first ability triggers and resolves, it immediately triggers again. (A so-called state-trigger, which is what Garruk's first ability is, does not trigger again while its previous instantiation is still on the stack. However, once it resolves, it's free to trigger again.)

This, technically speaking, causes an unstoppable loop that doesn't allow the game to continue. Every time the ability triggers and resolves (and fails to transform the clone), it immediately triggers again, and so on, ad infinitum. The game cannot proceed because of this, unless something kills the clone (such as someone casting a Lightning Bolt on it.)

The proper result of this would be that the game ends in a draw.

To attack, or not to attack?

Question: Assume you control a Jackal Familiar which is enchanted with Furor of the Bitten. You also control a second creature (that has nothing special to it.) Are you forced to attack with both creatures to make the Jackal attack?

Jackal Familiar can't attack or block alone. Furor of the Bitten says that the enchanted creature must attack each turn if able. Because of that last part, many players will intuitively answer that Jackal doesn't have to attack if nothing else is attacking, because it's not able to do so alone. Since it's not able to attack, it doesn't have to.

While this sounds logical and intuitive, it's actually incorrect. In fact, you have to attack with both creatures (if both are otherwise able to) in order to fulfill the requirement imposed by Furor of the Bitten. In a way, the combination of Jackal's and Furor's abilities causes a mandatory two-creature attack on each turn, if both of those creatures are able. (If Jackal is your only creature, or your other creatures can't attack for other reasons, eg. summoning sickness, then Jackal doesn't attack.)

This is one of the more obscure parts of the rules of the game, which often surprises players.

There is a rule that states that when declaring attackers, the player must declare them in such a way that fulfills as many requirements as possible. Since declaring two attackers (in this case) fulfills more requirements than declaring no attackers, the former is mandatory.

Note that this applies only to declaring attackers. If there are costs that have to be paid (eg. mana costs) in order for creatures to attack, those don't have to be paid. For example, assume that your opponent controls a Sphere of Safety.

In this case you are not forced to pay the mana cost required to attack, and thus your creatures are not forced to attack.

The exact rule that states this is the following:

508.1d The active player checks each creature he or she controls to see whether it’s affected by any requirements(effects that say a creature must attack, or that it must attack if some condition is met). If the number of requirements that are being obeyed is fewer than the maximum possible number of requirements that could be obeyed without disobeying any restrictions, the declaration of attackers is illegal. If a creature can’t attack unless a player pays a cost, that player is not required to pay that cost, even if attacking with that creature would increase the number of requirements being obeyed.

Optional abilities and targeting

Assume that you control a Phantasmal Bear and no other creatures, and then you cast Restoration Angel.

The question is: Do you have to sacrifice the Bear?

A good majority of players, even experienced ones, will say that no, because Angel's ability says "may." However, this is incorrect, and it's one of the most unintuitive aspects of the game (one which probably causes protest and disappointments from beginners.)

What's happening here is that when Restoration Angel enters the battlefield, its triggered ability will trigger regardless of whether you want to eventually use it or not. The optionality brought by the word "may" is only in effect when the ability resolves. (In other words, whenever a spell or ability says that you "may" do something, it means effectively "when this effect resolves, you may" do that thing.)

When an ability triggers, if it's a targeting ability, its controller must give it a legal target, if one exists. This is not optional. If there's only one legal target, that will be chosen for the ability. (The special case is when there are no legal targets. In that case the ability just "fizzles" and doesn't even enter the stack.)

Thus, if Phantasmal Bear is the only creature you control when you cast Restoration Angel, you have no choice but to target the former with the Angel's ability, regardless of what you would choose when said ability would resolve. As said, the choice is made only on resolution, not when the ability triggers.

And since Phantasmal Bear is being targeted by an ability, you have to sacrifice it. (The Bear's ability is also a triggered one, because it starts with "when", but it goes to the stack after the Angel's ability, and therefore resolves first. Thus the Bear is sacrificed before the Angel's ability has the chance to do its thing. And once the latter resolves, the Bear has become an illegal target because it's not on the battlefield anymore, and therefore the ability does nothing.)

Effects with multiple parts

Sometimes effects (usually spells or abilities) do more than one thing. The rule for this situation is that those things are done in the order they are listed in the card (rather than, for example, being done simultaneously.) In the vast majority of cases this is inconsequential, but there are a few rare cases where this causes rather interesting effects.

As an example, assume that there's an Elvish Champion and a Civic Wayfinder on the board.

As you may notice, the Elvish Champion boosts other Elf creatures (thus making the Civic Wayfinder a 3/3.)

Now someone casts Solar Tide and pays its entwine cost.

Because the entwine cost has been paid, both effects in the card will happen, ie. it will destroy all creatures with power 2 or less and all creatures with power 3 or greater. So what happens in this case?

Many players will hastily think that it simply destroys all creatures and that's it. However, as noted, if an effect has more than one part, they have to be evaluated in order. This particular situation requires a bit more analysis.

The first part of the spell, ie. "destroy all creatures with power 2 or less" is done first. The power of Elvish Champion is 2, and therefore it's destroyed. Civic Wayfinder is not destroyed yet because its power is 3.

As you may know, or remember from my previous blog posts, a destruction effect takes place immediately. It immediately puts the destroyed permanent into its owner's graveyard (unless some other effect interferes, such as the permanent being indestructible.) Therefore Elvish Champion leaves the battlefield when the first part of Solar Tide is performed.

Now the second part is performed. What happens? A bit surprisingly, Civic Wayfinder is not destroyed. This is because at this point Elvish Champion has left the battlefield and is not boosting Civic Wayfinder anymore, and thus the latter is now a 2/2.

Thus Civic Wayfinder survives the Solar Tide, even though at first it looks like it destroys all creatures.

Rockslide Elemental vs. Tephraderm

Consider these questions:

1. A Rockslide Elemental with four +1/+1 counters (making it thus 5/5) attacks, and a Tephraderm blocks it. Does the Elemental survive?
2. Would it make any difference if it were the Tephraderm that's attacking and the Elemental that's blocking?

Since the Elemental has first strike, it deals 5 damage to Tephraderm in the first strike combat step, which is lethal damage. Tephraderm does not deal combat damage (because it has no first strike), but its ability triggers, which deals 5 damage back to the Elemental when it resolves. When Tephraderm dies due to the lethal damage, Elemental's ability triggers which, when it resolves, gives it an additional +1/+1 counter.

Thus the question is: Which happens first, Tephraderm's ability dealing 5 damage to Elemental (which would then die), or the latter getting a +1/+1 counter (saving it)?

The answer can be quite tricky to figure out if one doesn't know the finest details of the game's rules.

One could naively think that since the Elemental deals damage first, Tephraderm therefore dies first and Elemental gets its additional counter, saving it. But then when one thinks a bit more, one realizes that at the exact moment that the Elemental deals combat damage to Tephraderm, the latter's ability triggers, and would deal damage back to the Elemental before its +1/+1 ability has the chance of triggering... And the train of thought can continue further from there, creating a chicken-and-egg problem.

A more experienced player can guess, correctly, that both abilities go onto the stack in APNAP order, but may not be able to tell precisely why.

("APNAP" order, or "active player, non-active player" order means that if two effects, controlled by different players, are trying to enter the stack at the same time, the effect of the active player goes to the stack first, and the non-active player then. They then resolve in reverse order, ie. the effect of the non-active player resolves first.)

So the core question here is when exactly does Tephraderm die. As you may know, and as I detailed in my previous blog post, a creature is destroyed from lethal damage only the next time that state-based actions are checked (which is different from eg. effects that say "destroy," which destroy the creature immediately.) Therefore the core question becomes: When exactly are SBA's checked here?

More precisely, the difficult question is: When Elemental deals its combat damage to Tephraderm, triggering the latter's ability, are state-based actions checked before or after said ability enters the stack?

This makes a big difference because if SBA's are checked only after the ability enters the stack, then the order of the two abilities is always the same. However, if they are checked before, then the two abilities are actually trying to enter the stack at the same time, and APNAP order applies.

The correct answer is that yes, state-based actions are checked between an ability triggering and it entering the stack. This means that when Tephraderm is dealt damage and its ability therefore triggers, before said ability enters the stack SBA's are checked and Tephraderm dies (due to lethal damage) triggering Elemental's ability. Therefore the two abilities are trying to enter the stack at the same time.

Therefore the correct answers to the questions at the beginning are:

1. No, Rockslide Elemental does not survive. This is because its ability is controlled by the active player (because the Elemental is attacking, meaning that it's being controlled by the active player) and therefore enters the stack first, and would therefore resolve after the Tephraderm's ability, which kills the Elemental before it gets the additional +1/+1 counter.
2. Yes, it makes a difference. If Elemental is defending, it means that it's being controlled by the non-active player, and therefore its ability enters the stack last, thus resolving first, and giving it an additional +1/+1 counter before Tephraderm's ability deals it 5 damage.

This is a detailed sequence of events:

• Rockslide Elemental assigns 5 damage to Tephraderm in the first-strike combat damage step.
• Tephraderm's ability triggers (but does not yet enter the stack.)
• State-based actions are checked, which cause Tephraderm to be destroyed due to lethal damage. Tephraderm is immediately put into its owner's graveyard.
• Rockslide Elemental's ability triggers due to Tephraderm dying (but does not yet enter the stack.)
• State-based actions are checked, but nothing special happens.
• The two abilities enter the stack in APNAP order. SBA's are checked, nothing happens.
• If Rockslide was attacking, it means Tephraderm's ability resolves first, assigning 5 damage to Rockslide. SBA's are checked and Rockslide is destroyed. Its own ability then resolves and fizzles.
• If Rockslide was blocking, then its ability resolves first, giving it an additional +1/+1 counter. Then Tephraderm's ability resolves assigning it 5 damage. However, since Rockslide is now 6/6, it survives.

Lethal damage vs. destruction

The rules of the games often contain nuances that can sometimes be confusing, if one is not aware of them. An example of such nuance is the difference between lethal damage and a destruction effect.

Consider these two questions:

1. There's a Dryad Militant on the battlefield, and someone casts a Searing Spear targeting (and killing) it. Where does the Searing Spear card go?
2. There's a Dryad militant on the battlefield, and someone casts a Doom Blade targeting (and killing) it. Where does the Doom Blade card go?

The Dryad Militant has an ability that says: "If an instant or sorcery card would be put into a graveyard from anywhere, exile it instead." One could easily think that in both cases the instant cards go to the graveyard because Dryad Militant has been killed and therefore is not affecting them anymore. Or perhaps in both cases they are exiled. However, it's not that simple.

The difference between the two cases is subtle, but crucial. The correct answers are:

1. The Searing Spear card is exiled.
2. The Doom Blade card goes to its owner's graveyard.

The reason for this is the difference between destruction and lethal damage (which in itself also causes the creature to be destroyed, but with a delay, as we will see.)

When an effect says that a permanent is destroyed, the destruction happens immediately when that effect is evaluated. There's no waiting for anything, or checking for state-based actions or anything; it's done immediately at that precise moment. Unless the permanent is indestructible or the destruction is somehow prevented (eg. with regeneration) the permanent is immediately put into its owner's graveyard.

When Doom Blade destroys Dryad Militant, the spell is still resolving, and the card is thus still on the stack. The Doom Blade card is put into its owner's graveyard as the last step of resolving the spell, but by that point Dryad Militant is not on the battlefield anymore and therefore it has no effect on the Doom Blade card.

However, when damage is assigned to a creature permanent, that damage doesn't do anything special at that precise moment. It's simply assigned to it (one could think of it as some "damage counters" being added to the permanent.) It's only the next time state-based actions are checked that said damage will destroy the creature (if it's lethal damage.)

State-based actions are not checked until after a spell has completely resolved. This means that Searing Spear will assign the 3 damage to Dryad Militant, which does nothing special to it at this point (other than marking the damage,) and then the Searing Spear card tries to go to the graveyard, but Dryad Militant's ability makes it go to exile instead. Only after that are state-based actions checked, and Dryad Militant is destroyed because of the lethal damage marked on it.

There are other situations that are even more confusing than this, and can sometimes cause confusion even among experienced players. For example, consider this problem:

There's a Tarmogoyf on the battlefield, a creature and a sorcery card in a graveyard (and no other cards), and someone casts Searing Spear targeting the Tarmogoyf. Does it die?

Tarmogoyf's power/toughness are 2/3 before Searing Spear is cast, and the latter deals 3 damage to the creature. So does it die or not?

Many players would say that yes. However, this situation is actually very similar to the one with Dryad Militant above. Like there, the subtlety in this situation is that state-based actions are not checked until after the Searing Spear spell has completely resolved, and putting the Searing Spear card in the graveyard is part of that resolution. Therefore the card is already in a graveyard when the checking is done whether Tarmogoyf is destroyed due to damage or not. At this point there are now 3 types of card in graveyards, and therefore Tarmogoyf is 3/4 and is not destroyed.

More shenanigans with Gideon and layers

This is a wonderful trio of cards because of how they interact with each other:

Gideon Jura and Mirrorweave are cards you should already know if you have read my previous blog posts. Veiled Crocodile is a slightly unusual card in that it's just an enchantment that by itself does nothing. However, it has a triggered ability that triggers when a player has no cards in hand, and that ability (permanently) makes it a 4/4 Crocodile creature. (Because it has no "in addition to its other types" it stops being an enchantment, or whatever other types it might have had besides a Crocodile creature.)

Question: Let's assume that Gideon Jura, whose third ability has been used, and Veiled Crocodile, whose ability has triggered earlier, are on the battlefield, and then someone casts Mirrorweave targeting Gideon. What happens to Veiled Crocodile?

One could hastily think that it becomes an unanimated copy of Gideon Jura, the planeswalker uniqueness rule kicks in, and both go immediately to their owners' graveyards.

However, that's not accurate. What happens is that Veiled Crocodile effectively becomes this:

In other words, it becomes a white 4/4 Crocodile creature named "Gideon Jura" with all of Gideon's abilities. It's not a planeswalker and the planeswalker uniqueness rule does not apply. Why?

As we saw in previous blog posts, copy effects happen on layer 1. In this case Mirrorweave is making the Veiled Crocodile permanent a perfect copy of the Gideon Jura card. However, Veiled Crocodile's triggered ability is still in effect, affecting the permanent (a copying effect does not affect any additional effects that may be applying to the permanent.) The type setting effect applies on layer 4, and the power/toughness effect applies on layer 7b.

Since the type setting effect has no "in addition to its other types", the copied type "Planeswalker - Gideon" is completely replaced with "Creature - Crocodile".

This is a rather interesting situation because now we have a non-planeswalker creature that has planeswalker abilities. Can they be used?

As far as I know, the answer is yes. There's nothing in the rules of the game that would forbid a non-planeswalker permanent from using planeswalker abilities if it somehow gains them, as is the case here. The same rules for using them apply, though (in other words, only one can be used per turn, and at sorcery speed.)

Obviously since the permanent has no loyalty counters at this point, only the +2 and the 0 abilities can be used. (Since using the former puts loyalty counters on the permanent, on a later turn if this situation is repeated, it could then use the -2 ability as well.)

What happens if the +2 ability is used? This is a rather unusual situation because the ability talks about something that's just not possible. It's not possible for any creature to attack this particular permanent because it's not a planeswalker (especially since the copy effect of Mirrorweave stops at the end of turn; but even if it didn't, it would make no difference: This is not a planeswalker permanent.) So in practice what happens is that activating the ability puts two loyalty counters on the permanent, and the ability just does nothing. (Creatures are not able to attack it, so they don't have to.)

(The above situation is actually one of the so-called "Magic Golden Rules." Namely, the one that says: "Any part of an instruction that's impossible to perform is ignored.")

If the 0 ability is used, the permanent becomes a 6/6 Crocodile Human Soldier creature. If you have read my previous blog posts you'll know why it retains the Crocodile subtype.

Another question: What if Mirrorweave had targeted Veiled Crocodile instead of Gideon Jura?

Again one could hastily think that Gideon Jura just becomes an unanimated copy of the Veiled Crocodile enchantment, and that's it. However, once again that's not exactly what happens. Instead, it becomes this (I took the liberty of modernizing the card a bit):

As in the other situation, Mirrorweave's copy effect applies on layer 1, and the type setting effect of Gideon is still in effect on layers 4 (setting the type to Human Soldier creature) and 7b (setting the power/toughness to 6/6.) It also retains the Enchantment type because the type setting effect says "is still a planeswalker" which, as we saw in previous blog posts, is a synonym for "in addition to its other types."

In other words, Gideon becomes a blue 6/6 Human Soldier enchantment creature named "Veiled Crocodile", and which has Veiled Crocodile's triggered ability.

If said ability triggers, a new type setting effect is applied. Since it applies on the same layers as Gideon's third ability, but has a newer timestamp, it overrides Gideon's ability and his type becomes "Creature - Crocodile" and his power/toughness is set to 4/4.

A hole in the MtG rules?

Suppose that the card Wild Evocation is on the battlefield.

At the beginning of each player's upkeep, that player reveals a card at random, and if it's a land card, puts it onto the battlefield, else the player casts it without paying its mana cost. This is not optional. The card must be cast if possible (that is, if it's a spell that for example targets something, if there is something legal that it can target, it must be cast targeting one of those things.)

The casting is so mandatory, in fact, that if casting has some mandatory additional costs, they must be paid if possible. The oracle rulings state:

If casting the revealed card involves paying a mandatory additional cost (such as the one Fling has), the player casting that card must pay that cost if able.

This isn't optional either.

Now, what happens if the revealed card is, for example, Disaster Radius?

The mandatory cost of revealing a creature card must be paid if the player has a creature card in hand. However, a player cannot be forced to reveal their hand to corroborate that they don't have such a card. (No effect in either card requires the entire hand to be revealed, and no rule allows other players to demand the entire hand to be revealed.)

So how is this situation handled? How to corroborate that a player is telling the truth if they claim that they have no creature cards in hand?

The answer is that the rules of the game simply don't cover this situation. In other words, the rules do not offer any standard mechanism for other players to corroborate the situation.

The only thing that the other player or players can do is to ask a judge to examine the player's hand, if in a tournament setting, or if in a casual setting either simply trust the other player or ask an impartial third party.

Not that this situation is at all common, but I find it interesting that there's something that the rules of the game just don't cover.

Update: A rule introduced with Magic 2014 will cover this precise situation. The new rule will be that the player will not be forced to reveal hidden information (and thus, if the player chooses not to, he or she doesn't cast the card.)

Type and P/T setting effects made easy

As seen in my previous blog post, effects that set or change the types and power/toughness of a permanent can sometimes cause confusing situations. Here are some rules of thumb that can be used to make understanding these situations easier.

1. If an effect says "is/becomes a (type)" (with no "in addition to its other types"), all of that permanent's types are replaced with the new one. (For example, if it was a "Land Creature" and the effect says that it "becomes a creature", then it would lose the Land type.) All of the subtypes are likewise replaced by this.
2. If an effect only sets a subtype with "is/becomes a (subtype)" without mentioning a type (and without any "in addition to its other types") then only the subtypes of that particular category are replaced with the new subtype. (For example, if the type of the permanent was "Land Creature - Forest Dryad" and an effect says that it "becomes a Treefolk", then the type becomes "Land Creature - Forest Treefolk.")
3. If the effect in question says "in addition to its other types" or "is still a X" then it retains all of its previous types (completely regardless of what that X is.) The latter expression means the exact same thing as the former one. Also, the latter expression never adds any type to the permanent, even if it might sound so. (For example, "it's still a land" does not add the Land type to the permanent. It simply means that it retains all of its existing types.)
4. There's a specific exception to the first rule above. If an effect says that a permanent "becomes an artifact creature", then it retains all of its existing types without that effect having to say so. (This is a special exception stated by the game rules.)
5. A copy effect replaces everything in a permanent with the contents of another card, and this happens on layer 1. Effects that set or modify the type of the permanent happen on layer 4 (and thus are applied on top of any copy effect that may have been applied.) Effects that set or modify the power/toughness of a permanent happen on layer 7 (on different sublayers depending on the kind of effect.) If two effects would set or modify the same thing on the same layer or sublayer, the one with the newest timestamp wins. If two effects would get the same timestamp (eg. because they are entering the battlefield at the same time) the active player decides their order.

(Note that copy effects and layers are more complex than this, but those details are beyond the scope of this short list.)

Fun with Gideon and layers

Gideon Jura is one of the most interesting planeswalker cards because he has a rather particular ability: He can (temporarily) become a creature. (It's certainly possible to make any planeswalker permanent into a creature via trickery, but Gideon doesn't need the trickery because it's directly one of his abilities.) This allows very interesting interactions and situations both in the game mechanical and the flavor sense.

What exactly happens when Gideon's third ability is used? The question seems rather self-evident (he "becomes a 6/6 Human Soldier creature that's still a planeswalker"), but it's in fact a bit of a complicated issue because it has to do with the concept of layers. In the vast majority of cases one doesn't need to care about this at all, as a straightforward approach is enough to get it right. However, let's examine what's happening a bit in more detail.

An interesting question is: What's Gideon's entire type line and power/toughness after the third ability has been used? While there is no existing template for a card that's both a planeswalker and a creature, it would nevertheless be something along the lines of this:

In other words, his entire type line is:

Planeswalker Creature — Gideon Human Soldier

He is both a planeswalker, of subtype Gideon, and a creature, of subtypes Human Soldier. As a creature, his power and toughness are 6/6.

Ok, so far there's nothing special about this and, as said, this suffices for the vast majority of cases. However, there are situations where this becomes a lot more complicated.

There exists a wonderful card named Mirrorweave, which is an instant that says: "Each other creature becomes a copy of target nonlegendary creature until end of turn." This card is wonderful because it allows making any creature a copy of any other creature, resulting in really interesting shenanigans with respect to the layering system of the game.

Let's assume that in addition to Gideon Jura (whose third ability has been used), there's for example a Grizzly Bears on the battlefield. It looks like this:

Now someone casts Mirrorweave targeting Grizzly Bears. What exactly happens to Gideon?

A good majority of players would hastily say that Gideon just becomes a perfect copy of Grizzly Bears, and that's it. In other words, he becomes a green 2/2 Bear creature (with converted mana cost 2, and named "Grizzly Bears".) However, that's not correct. The correct answer is that he becomes this:

In other words, he becomes a green 6/6 Bear Human Soldier creature (with CMC 2, named "Grizzly Bears", without abilities, and that's not a planeswalker.) But why?

The answer is a bit complicated, and has to do with layers.

Mirrorweave's copy effect is applied on layer 1, ie. before anything else. This makes the Gideon Jura permanent a perfect copy of the Grizzly Bears card (all of the copyable values are copied.) None of the contents of the Gideon Jura card are retained because the copying effect replaces them all (which is why he stops being a planeswalker, alongside everything else.)

However, the story doesn't end there. Gideon's third ability is still in effect (because once it's activated it applies to the permanent until end of turn, no matter what else is applied to the permanent in addition.) Said effect says that he "becomes a 6/6 Human Soldier creature."

The creature subtype setting effect is applied on layer 4, making him a Human Soldier, and the power/toughness setting effect is applied on layer 7b, making him 6/6. In other words, these two effects apply on top of Mirrorweave's copying effect.

There's still one small catch. Namely: Why is he still a Bear, if his own ability is making him a Human Soldier?

This is a very relevant question because normally if an effect sets the subtype of a permanent, it replaces any subtypes of the same category that permanent may have had. For example, if Gideon were to now be enchanted with Lignify, which says "enchanted creature is a 0/4 Treefolk with no abilities", his type would become "Creature - Treefolk". All of his existing subtypes would be replaced by Treefolk. (The type setting effect of Lignify trumps Gideon's because it has a later timestamp.)

Therefore the question is: If Gideon's third ability says that he "becomes a 6/6 Human Soldier creature", then why does he retain the Bear subtype?

The reason for this is that the effect in question is, actually, "becomes a 6/6 Human Soldier creature that's still a planeswalker." That last part is crucial. As unintuitive as it may sound (and it indeed is quite unintuitive), "is still a planeswalker" means that he retains any types he might have in addition to gaining "Human Soldier creature".

There's a section in the comprehensive rules that states, basically, that "is still a X" is a synonym for "in addition to its other types" (completely regardless of what that X might be.) Therefore whenever you read "is still a X" in a card, it's completely equivalent to it reading "in addition to its other types" instead. For this reason Gideon retains the Bear subtype in this situation. (Perhaps a bit confusingly "is still a planeswalker" does not add the planeswalker type. It's not an effect that adds anything.)

This peculiarity, however, allows some rather interesting situations flavorwise. For example, let's assume that instead of Grizzly Bears, the other creature had been a Dryad Arbor:

If Mirrorweave were targeting that, what would Gideon Jura look like? This:

In other words, his type line becomes:

Land Creature — Forest Dryad Human Soldier

Because "is still a planeswalker" means that he retains all of the types that Mirrorweave copied, he is now a Forest land in addition to being a Dryad Human Soldier creature. Yes, he can tap for one green mana (but has no other abilities.)

Also, curiously, since he's not a planeswalker at this point, you can cast another Gideon Jura without the planeswalker uniqueness rule kicking in, so you can have two Gideon Jura cards on the battlefield at the same time (but only until end of turn, of course.)