Cranial Insertion: All About Triggered Abilities
By Ted Dickinson on October 30th, 2006 · Filed in Cranial Insertion · Comments not available just now
All About Triggered Abilities
or, Whenever You're Time-Traveling, Think About When to Look At
By Eli Shiffrin, Tom Fowler, and Ted Dickinson
Are you lazy? Do you hate having to activate or cast things to have fun? Are you looking for effects that can win you the game without having to lift a finger?
Then have I got a deal for you!
Through the ancient Magicese tradition of triggered abilities, objects can go on the stack automatically!
Q: So, what's a triggered ability anyway?
A: There are two major kinds of triggered abilities.
The first kind begins with “when” or “whenever.” These abilities trigger when something happens in the game, which is described in the triggered ability before the first comma.
For example, let's look at the rules text on Abyssal Nocturnus:
Whenever an opponent discards a card, Abyssal Nocturnus gets +2/+2 and gains fear until end of turn.
It's clearly a triggered ability as it starts with “Whenever.” The event that causes it to trigger is “an opponent discards a card.” So when this creature is in play, and an opponent discards a card, this triggered ability will go onto the stack right before the next time a player would gain priority. Since players don't normally gain priority during the resolution of a spell or ability, that means these abilities often have to wait for something that's currently resolving to finish before they go on the stack.
If an ability triggers while another spell or ability is resolving, it waits until that spell or ability is completely finished resolving before it goes on the stack.
That last point bears repeating in big bold letters over at the right-hand side of the page because it answers many of the most frequently asked questions regarding triggered abilities.
The second kind of triggered ability starts with “At.” These abilities trigger when the turn or game reaches a certain point, often the beginning of a step or phase. For example, Dark Confidant has an ability that triggers “at the beginning of your upkeep:”
At the beginning of your upkeep, reveal the top card of your library and put that card into your hand. You lose life equal to its converted mana cost.
Abilities that trigger at the beginning of a phase or step go on the stack before a player would gain priority, so nobody has an opportunity to play anything beforehand.
Even abilities that look like they trigger “at” the end of something really trigger at the beginning of a step. “At end of turn” abilities (like the ability on Psychic Vortex that makes you discard your hand actually triggers at the beginning of the “end-of-turn” step.
These “at” abilities usually only get one chance to trigger per turn unless something is monkeying with the progression of the game (like Paradox Haze). If they're not already in play at the appropriate time, they have to wait around for the next opportunity. For example, if our Dark Confidant comes into play during the upkeep step thanks to something like Corpse Dance, it missed its chance to whisper evil nothings in your ear.
Once a triggered ability goes on the stack, players can play spells or abilities in response to it just like they can respond to spells or activated abilities. Except. . . .
Q: My opponent has a Forest enchanted with Utopia Sprawl. I know I can't Ghost Quarter it in response to him tapping it for mana, but can I destroy it in response to him getting mana from Utopia Sprawl?
A: No. Now don't interrupt!
Many players are familiar with activated mana abilities: they're activated abilities that could put mana into a player's mana pool when they resolve. The most basic of these are the activated abilities of each of the basic lands. These abilities don't use the stack so nobody can respond to them.
However, they're not the only mana abilities out there.
Some abilities trigger when someone plays an activated mana ability that produces mana. Many such triggered abilities, like that of Utopia Sprawl, also put mana into a player's mana pool. These are also considered mana abilities by the rules. Just like activated mana abilities, triggered mana abilities don't use the stack so nobody can respond to them.
You'll just have to sit and wait to use that Ghost Quarter.
Q: So I guess that means that when I tap an Island for mana while Manabarbs is out, I can't use that Blue mana to Stifle the triggered ability?
A: Sure you can, if you really want to. For a triggered ability to be a mana ability, it has to fulfill both of those criteria:
1)The trigger event for it must be the playing of an activated mana ability, AND
2)The triggered ability must also produce mana when it resolves.
Manabarbs doesn't have a triggered ability that produces mana, so it's not a mana ability. It uses the stack just like the ability on Abyssal Nocturnus.
Q: So what happens when I have out 4 Manabarbs at once? Are they cumulative?
A: Many questions about what happens when multiple abilities trigger at the same time ask if they're “cumulative” or they “stack.” While the answer is yes, I find it best to avoid that terminology and look at what's really going on according to the rules.
Whenever multiple abilities trigger simultaneously, they go on the stack in what's called “APNAP order.” That's short for “active player/nonactive player.” Effectively, the active player (the player whose turn it is) puts triggers he or she controls onto the stack, then the nonactive player does this same with triggers he controls. If a player has multiple triggers to put onto the stack, that player specifies their order.
Even if multiple triggers have the exactly the same effect, each one is a separate object on the stack. This is why I suggest players not think of multiple triggers as being “cumulative”; that implies that the separate abilities somehow combine into one single large effect, which isn't the case and is an important difference when things like Stifle become involved. And saying they “stack” is especially confusing because the word “stack” means something completely different in Magic-land.
Q: I control a Mishra, Artificer Prodigy. I played a Chromatic Star from my hand and my opponent countered it. Is it still considered played?
A: A spell is considered “played” as soon as the player has completed all the steps of Formula 409 (that's Section 409 of the CompRules, not to be confused with the cleanser) for playing it: putting it on the stack, choosing modes and targets, paying costs, and so on. After that, and immediately before any player gets priority, Mishra's ability is put on the stack. Then you get priority as the active player.
By the time you yield priority to your opponent so they can play their counter, your Mishra trigger is already on the stack and waiting to resolve. Countering the spell doesn't “unplay" it.
Not only do you still get to resolve your Mishra trigger, you can choose to search your graveyard for the very same Chromatic Star that was just countered and put into into play. Take that, Artifact Blast!
Q: OK, I'm confused. Thicket Basilisk's triggered ability says it triggers when the creature blocks or is blocked, but it does something “at the end of combat!” That looks like two different triggered abilities.
A: You're almost right. It's actually one triggered ability that creates another one.
Just as it says, Thicket Basilisk's triggered ability goes on the stack when it blocks or is blocked. However, when the triggered ability resolves, it doesn't immediately do anything to the game state. The creatures it's tied up in combat with are still in play.
What this ability does when it resolves is create another triggered ability, called a “delayed triggered ability.” The series of rules that deals with these can be found under Rule 404.4:
There's a bit to digest there. Go ahead, I'll wait.
What all that really means is that, when the triggered ability of Thicket Basilisk resolves, it makes another triggered ability that just sits around waiting for the beginning of the “end-of-combat” step. Then, when that time comes, it springs into action and goes onto the stack. When this second triggered ability resolves, all those creatures unfortunate enough to stare down the Thicket Basilisk are going to get petrified all the way to the graveyard.
Q: Can I play a Cloudchaser Eagle when there are no enchantments in play?
A: Yes. Most players know that they can't play a spell or activated ability that requires a target when there aren't any legal targets to be chosen. Players sometimes unconsciously extend this to permanents with “comes into play” triggered abilities and think that they can't play the spell if there's no target for the ability.
The reason Cloudchaser Eagle is different from, say, Demystify in this regard is that the Cloudchaser Eagle spell doesn't target anything at all. All the spell does is turn into a creature when it resolves. The ability on Cloudchaser Eagle is separate from the spell.
Q: So what happens to that triggered ability if it doesn't have a target?
A: What actually happens here is explained by Rule 410.4:
In other words, the triggered ability quietly sulks away into oblivion while the 2/2 flying bird hangs around to see the sights and maybe get involved in a light tussle.
Q: So when the Eagle comes into play, can I just choose not to destroy anything at all?
A: Not if there's anything to destroy. You have to choose a legal target if one exists, even if the triggered ability has text to make it optional (frequently a phrase like “you may”).
If the ability is optional (which Cloudchaser Eagle's isn't), then you can opt not to perform the action when the triggered ability resolves, but you still have to choose the targets when it goes on the stack.
Q: What about something like Genesis? It's got an optional triggered ability but there's a mana cost involved.
A: You still have to choose a creature card in your graveyard if you have one that can legally be targeted. (Get thee behind me, Ground Seal!) You don't have to decide whether to pay mana until the ability resolves. If you pay the mana, the creature card goes to your hand. If you don't, it just stays where it is.
Q: I have out an Oath of Druids and two creatures while my opponent only has one creature. After I put my Oath trigger on the stack he Terrors one of my creatures. I still get to Oath, right?
A: Not exactly.
Oath of Druids is a great example of what's called an “intervening-if” clause. These clauses tack an additional condition onto the event which causes an ability to trigger. In this case, having it in play at the beginning of your upkeep isn't enough; you also need to control fewer creatures than your opponent. If the “intervening-if” clause isn't met, then the ability won't trigger at all regardless of whether the event happens.. So if you have the same number of creatures as your opponent, that Oath trigger never even goes onto the stack.
However, that's not the only time an “intervening-if” clause is relevant. The additional condition . . . al (sorry, the rhyme was too good to pass up) is also checked again as the triggered ability begins to resolve. If the condition is no longer true, then the ability doesn't do anything when it resolves. (Note that this isn't “fizzling” as we discussed earlier with targeted spells and abilities. The ability isn't countered; it just doesn't do anything.)
So in this example, even though your Oath trigger still resolves, you don't get to do anything with it.
Q: So if my opponent puts his 20th charge counter on Darksteel Reactor, I can Stifle the ability that wins him the game, right?
A: You can Stifle it . . . you just won't get the result you'd like.
The triggered abilities we've been talking about so far trigger on an event in the game. The first triggered ability on Darksteel Reactor is one of those: it triggers at the beginning of each of its controller's upkeep steps.
The second triggered ability, though, triggers when something about the game state is true, not necessarily when an event happens. These are known as “state triggers.” As soon as the game state reaches the appropriate point (in this case, when Darksteel Reactor has 20 counters on it), the triggered ability will go on the stack right before the next time a player would gain priority.
The ability will not trigger again until this first triggered ability leaves the stack. This is necessary to prevent the game from immediately entering a loop of mandatory actions, which would cause the game to end in a draw.
However, when the triggered ability does leave the stack for any reason, it will trigger again as long as the game state still matches what the ability is looking for. This doesn't happen much with Darksteel Reactor as the first resolution of the triggered ability normally causes its controller to win the game. However, if the ability leaves the stack for some other reason (such as being Stifled), it will go back on the stack before a player can get priority again.
In short, Stifling the winning triggered ability on the Reactor doesn't do much because your opponent will just get that ability back on the stack immediately afterwards.
Now, let's apply some of what we've learned about triggered abilities to a real question from the email@example.com mailbag.
A: Remember that big bold text from earlier? Here's a great application of it.
I have a Thrumming Stone in play, and I play a Relentless Rats. Since the deck has 22 Relentless Rats, I end up rippling into 4 more Relentless Rats. I then Play the first of the rippled Rats and ripple 2 more. How do I resolve the ripple triggers? Do I resolve all 4 Rats first and reveal the top 16 of my library or do I do them one at a time, resolving any other rats that I happen to ripple?
The Relentless Rats are considered played once you've put them on the stack and paid all the costs. Then the Ripple trigger goes on the stack “on top of” the Rats. When that trigger resolves, you reveal the top four cards of your deck and can play any that are also called Relentless Rats. Assuming all four cards you reveal are Relentless Rats and you choose to play all four of them, you cause Ripple to trigger four more times.
However, keeping in mind the big bold text from earlier, the first Ripple ability has to completely finish resolving first. Once that's done, the active player would gain priority, but now there are four more Ripple triggers.
The stack would at that point would look something like this:
So what would happen if you resolved the first of those Ripple triggers and revealed two more Relentless Rats? It would then look like this:
Much more of this and the stack will be too silly to type out.
OK, so maybe triggered abilities aren't absolutely free. But sometimes, you get what you pay for!
So wow your friends! Confound your opponents! Harness the power of the trigger today*!
*Power is figurative. Darksteel Reactor doesn't power real-life electrical equipment. Your mileage may vary. Results not guaranteed.
Join us next week, when we talk about Standard!
By Ted Dickinson on October 30th, 2006 · Filed in Cranial Insertion · Comments not available just now