Order of Operations (The Old Version!)
or, Don't Touch the Sides
By Eli Shiffrin
Order of Operations (The Old Version!)
or, Don't Touch the Sides
By Eli Shiffrin
[IMPORTANT NOTE: This article is rendered incorrect by the July 2009 Comprehensive Rules update. So why are we republishing an old article? Simple: Many people have established bookmarks and links to the original article, and we'd rather those be valid, but we wish to preserve the original article for rules-historical purposes.
So this article is a reprint of how the layer system worked before Magic 2010.
***** For Cranial Insertion's updated Order of Operations article, click here. *****
You can read on if you wish to read the old article, or click the link above to read the new one. The biggest changes there are the new layer 6 and the redistribution of layer 7, but you might as well re-read the whole thing - it's fun! And I've made some sneaky little changes throughout to up the amusement value for those of you re-reading it. Join us next week when Paskoff riffs on the heavy nature of M10 and fields a hurricane of mailbox questions!]
Welcome back for another edumacational article! We're going to up the education level in this article by holding off on all of the questions you've sent in and focusing on a topic that is pertinent to many of the questions you've asked; a topic we've covered no fewer than three times in the past but that continues to be a problem; a topic that fills many of you with dread and fear. We're going to discuss . . .
We'll be back next week with more questions from the [email][email protected][/email] inbox, so mail in your questions if you want them published in that article or if you just want an answer!
Yup, layers. In real life, if you splash a wall with coats of paint over and over, not only do you completely ruin the drywall and face vandalism charges, you end up with the last-applied coat of paint as the only one showing. But Magic is not a wall, no matter how much you feel like banging your head against it sometimes. In Magic, like in mathematics, some functions are simply applied first.
To go with an analogy that doesn’t involve your Dear Aunt Sally (whom we won’t excuse, since she hates monkeys), all of these continuous effects are a bunch of unruly toddlers drooling snot on your cards. They have to line up in order by height.
The system of layers defines that order of operations, or the heights of those toddlers. It tells you the order to apply continuous effects in, regardless of the order in which they were created or started to apply. That is, the stack may resolve last-in-first-out, but continuous effects do not, and the last-created effect may be applied first, last, or anywhere in between.
Of course, the order in which effects were created does have some relevance. Within each of the layers that we're about to dig through, multiple effects may exist that belong in that layer. This collision is resolved 99% of the time by the order in which effects started to apply – that is, in "timestamp" order. So if you have one effect that says "Target creature is red" and then you create another effect that says "Target creature is blue," the last one to be created will win: the creature is blue.
An effect's timestamp is the relative time it started to apply. For an effect generated by a permanent's static ability, like Glorious Anthem, that timestamp is when the permanent came into play. For an effect generated by a resolving spell or ability, that's the time the spell or ability resolved.
But for an effect given to an enchanted, equipped, or fortified object, the timestamp is the time the Aura, Equipment, or Fortification became attached to that object. If you move your Leonin Scimitar around amongst your creatures, the continuous effect it generates will have a new timestamp each time someone snatches it away from someone else.
What Happens in Each Layer?
I said that timestamps resolved intralayer collision 99% of the time, but that other 1% is important to have rules to cover. Otherwise, 1% of the time, the game would explode! In fact, that 1%, whenever it comes up, has to be taken into account before timestamps. Timestamps are a last resort to sort out effects in one layer.
Start from the top of the layer list and work your way down. As you enter each new layer, the first things to apply are characteristic-defining abilities. Characteristic-defining abilities. Too many letters. They're CDAs, so say we all.
A CDA is pretty easy to recognize. The most common one is on our good friend Tarmogoyf: it has an ability that sets its power and toughness. That's a CDA! CDAs define an object's power, toughness, subtypes, or color. They also have to be a part of the object itself, so Aphotic Wisps does not produce a CDA, but Ghostfire does have a CDA. Changeling has the distinction of being a keyworded CDA! So, with these two criteria in mind, you can pick out almost any CDA. There is one exception that will very, very rarely pop up: If the ability is conditionally on/off, it can't be a CDA.
Well, That Depends
After you apply all of the CDAs, but before you look at timestamps, you run into one of the bogeymen of the layer system: dependency.
Dependency can be a real headache for even grizzled rules veterans. Here's the quickest, possibly easiest way to break down dependency:
Effect A depends on Effect B if both A and B are applied in the same layer and one of the following conditions is true:
- Applying B first causes A to no longer exist.
- Applying B first causes A to apply or not apply to object X.
- Applying B first changes how A works (but not how much A works).
Oh, you want an example, don't you? Look at Blood Moon and Urborg, Tomb of Yawgmoth, a classic example of dependency. Applying Urborg's effect makes things Swamps, but applying Blood Moon's effect changes Urborg's subtype. Since setting land subtypes strips that land of its native abilities, Urborg will lose its ability to make Swamps if you apply Blood Moon first! This falls under the first bullet point above: Blood Moon's effect causes Urborg's effect to cease to be. You must apply Blood Moon first, and then Urborg's effect no longer exists: it can't be applied anymore.
The undisputed king of disgusting
The undisputed king of disgusting
Another extremely useful example is Corrosive Mentor and Aphotic Wisps (which was played on a monowhite creature). Corrosive Mentor's effect applies in the same layer as Aphotic Wisps’ effect, but applying the Wisps' effect first makes the monowhite creature monoblack – and thus Corrosive Mentor's effect can apply to it! Oh goodie! So the Mentor's effect depends on the Wisps', and the Wisps' effect must be applied first.
So I'm sure you're wondering why this is all so complicated. The reality is that this system of complication produces very natural results. Without dependency, your now-black creature in the second example would not have wither, despite being black. That is strange, counterintuitive, and not what the game's designers wanted. This also means that in most cases, you can guess how things will interact and you'll be right. Keep that in mind when you run into a strange situation where this system produces unintuitive results – they're bound to pop up from time to time, and the number of intuitive results greatly outnumbers the unintuitive ones.
Smash It Up
CDAs, dependency, and timestamp. You have the backbone of the layers, but there's one more thing to mention before we start adding flesh to these vertebrae. Let's look at Viridescent Wisps, Aphotic Wisps' naughty brother. The creature not only becomes green, it also gets a power/toughness modification! If you've read ahead, you know that color-setting and power-modification apply in different layers, but here they're on one effect. Well, that's just fine. Break this effect up into its component pieces! Those pieces will be applied in the appropriate layers, and not all applied at once. The pieces of an effect, once broken up like this, will still be applied, even if the effect itself vanishes along the line (which can happen quite "easily" with Humility and Opalescence)
Layer 1: Copy
Let's start our journey through the wonderful world of the layers!
The first layer is the layer of copy effects. This is quite simply anything that says "becomes a copy," including Mirrorweave and Clone. But two other sneaky types of effects creep in here, too.
- Before you apply copy effects, apply effects like Aquamorph Entity's: effects that are generated by a replacement effect that replaces coming into play or being turned face up by setting a characteristic.
- After you apply copy effects, apply effects from face-down status, like morph or Illusionary Mask.
Example: Adam controls a 2/2 flying Primal Clay, and then he plays Ixidron, turning Primal Clay face down. Primal Clay was a 2/2 flying creature, but now it's a 2/2 nameless creature with no abilities. Eve plays Clone copying this creature, but Clone is a face-up 2/2 ability-free creature since these face-down values are copiable.
Example: Cain controls four face-down creatures, and Abel plays Mirrorweave targeting his Llanowar Elves. Cain's face-down creatures would be Llanowar Elves, except that since they're face down, they're 2/2 blanks instead (and he can't turn them face up, since Llanowar Elf doesn't have a morph cost). If Abel plays Break Open on one later in the turn, it'll be a Llanowar Elf when it's face up.
Example: Lillith plays Clone and chooses to copy Sengir Vampire. Sengir Vampire dies in a bloody splatter (perhaps it was blocked by something unspeakable), so she plays another Clone, choosing to copy the first Clone. Since copiable values look like the end result of layer 1, the new Clone will be a Sengir Vampire, even though no creature card naturally known as a Sengir Vampire exists in play.
Layer 2: Control
The control layer is extremely simple. It's where you apply all effects that change control of an object. That's it. No shenanigans.
Example: Happy controls a Birds of Paradise. Grumpy plays Confiscate on it, so Grumpy controls it. Then Sleepy plays Control Magic on Birds of Paradise. Sleepy's enchantment has a later timestamp, so he controls the Birds now. But then Sneezy Threatens the Birds, so his latest timestamp controls the Birds. If Dopey Disenchants Control Magic before Threaten's effect ends, the only effect still applying after this turn will be Grumpy's Confiscate, so he'll get the Birds back.
Example: Bashful plays Confiscate on Happy's Birds, since the dwarves obviously play silly free-for-all games with a staggering amount of Blue-based control decks despite their inherent weakness in multiplayer formats. Doc plays Confiscate on Bashful's Confiscate, though! Since Doc's Confiscate's effect changes what Bashful's Confiscate does (it changes who it gives control to), Bashful's Confiscate's control-change effect won't be applied until after Doc's Confiscate has confiscated Bashful's Confiscate and that Confiscate gives "you" – Doc, its controller – Happy's Birds.
(Meanwhile, Snow White is sitting in the corner crying her eyes out because she doesn't have any halfway decent opponents to test her Faeries deck against. One day her prince will come, but little does she know, he'll be a Vintage player.)
Layer 3: Text
The third layer gets complicated again, sort of. The text layer is a layer for text changes. This means exactly that: effects that change text. It's not a place for gaining or losing abilities (text may create abilities, but abilities don't create and are not text). It's just text changing, like Mind Bend and Artificial Evolution. Volrath's Shapeshifter also fits into this layer, since it gains text, and not abilities, of the card in your graveyard. You'll notice that all of these cards specifically reference "text" – that's the key to fitting in here.
Example: Augustus plays Confiscate on Johannes' Volrath's Shapeshifter. Since Confiscate's effect is a control effect, it's already been applied back in layer 2, and Volrath's Shapeshifter uses its new controller's graveyard to determine what it is – as most players would expect.
Example: Andreas, being a terribly indecisive individual, has played three Mind Bends on his Zodiac Horse. The first one's effect changes "Island" to "Forest." The second's changes "Forest" to "Swamp." The third's effect changes "Swamp" to "Mountain." These are applied right through in timestamp order: all instances of "Island" (in islandwalk, the only "Island" on the card) become "Forest," then become "Swamp," then become "Mountain."
Example: Laurens, always trying to top everyone else, plays Grayscaled Gharial on MTGO, then Mind Bends it, but misclicks and changes "Swamp" to "Forest." Trying to be clever, he plays a second Mind Bend changing "Island" to "Swamp." MTGO says that his Gharial has swampwalk now, and not forestwalk, so he writes a ten-page dissertation on why MTGO sucks and how it never handles the rules correctly because these two effects are dependent on each other, and goes on to tell judges all over the world that these effects are dependent because that's how it works on MTGO. But he's wrong. Remember that changing how much work an effect performs does not change what it does, so there is no dependency here. The first Mind Bend's effect is applied and does nothing, then the second's is applied.
Layer 4: Type
This layer would be an easy layer – just apply all effects that change, give, or take away supertypes, card types, or subtypes – except that this is the layer where you run into all sorts of dependency issues.
Example: Titania controls Titania's Song (she hasn't sold out yet) and Mycosynth Lattice. Since the Lattice causes the Song to apply to exciting new permanents that it wouldn't otherwise apply to, the Song's effect is not applied until after the Lattice's effect.
Example: Oberon controls a Skeletal Changeling and Humility. Since we haven't gotten around to any layer that removes abilities (don't worry, it's coming up), Humility's effect hasn't been applied yet. Skeletal Changeling has all creature types, even though it's about to lose the changeling ability.
Example: Puck uses Unnatural Selection to turn Chameleon Colossus into a Goat. Since Unnatural Selection's effect applies after changeling, the Colossus will be only a Goat.
Layer 5: Other Stuff
If you've been walking down Layer Avenue with me, you can figure out what goes in here easily enough: it's any effects affecting objects but that don't fit in the first four layers and that don't modify power and toughness. This is most commonly adding abilities (Corrosive Mentor), and more rarely subtracting abilities (Humility) and changing color (oh hai all you Wisps).
Example: Sheldon controls Opalescence and Humility because he's hardcore like that. Since Opalescence's type-changing effect was applied back in layer 4, Humility is now a creature and it will strip itself of its own abilities when its effect is applied. Nevertheless, the "we're all 1/1" part of its effect will still be applied later on in layer 6. When we started applying Humility's effect and broke the effect up, this fragment drifted off instead of waiting around to be erased - even though Humility no longer has the ability, the effect has started to apply and all parts of it will be applied.
Ach, Hans, run!
Ach, Hans, run!
Example: Collin plays Empty-Shrine Kannushi, and then hits it with Cerulean Wisps. Since the Wisps’ effect changes what the Kannushi's effect does (what sort of protection it grants), the Kannushi's effect won't be applied until after it becomes blue, and it will have protection from blue instead of protection from white. Look, an intuitive result! Aren't they cute?
Example: Gis plays Ovinize on Toby's Mass of Ghouls that has a Helm of Kaldra attached. This works by timestamp – Mass has no abilities now. If Toby plays the Helm's equip ability targeting Mass of Ghouls, it won't become attached again (it's already attached!) so nothing happens. But if Toby attaches the Helm to another creature and then reattaches it to Mass of Ghouls, the Helm's effect will have a later timestamp than Ovinize and he'll have a fabulously useless 0/1 creature with first strike, trample, and haste.
Example: Mike is feeling educational, so he Confiscates a Spitting Slug, turns it into a Faerie with Unnatural Selection, and then plops out a Scion of Oona. Confiscate snags the slug in layer 2, and then the slug grows non-functional Faerie wings in layer 4, so by the time the Scion gapes in horror at this gooey, slimy fake Faerie, it's "a Faerie" that "you control," so it gets shroud from the Scion.
Example: Jaap controls Corrosive Mentor and Saffi Eriksdotter. He uses Aphotic Wisps to dress Saffi in black, but then decides that she would look much cuter in blue so he plays Cerulean Wisps. Now we have an interesting dependency: Corrosive Mentor's effect depends on Aphotic's effect since Aphotic's effect makes the Mentor's apply, but it does not depend on Cerulean's – yet. First Aphotic's effect makes Saffi black, and then we look again. Now the Mentor's effect depends on Cerulean's effect since it makes it no longer apply! Apply Cerulean's effect, and then Mentor's effect won't apply anymore. The end result is a blue creature without wither, as we'd expect.
Example: Blades of Velis Vel says that the creatures "gain all creature types" and not "gain changeling." If they gained changeling, they'd gain it here in layer 5 – after type-changing effects have already been applied. So changeling would never do anything, and Blades has the wording it has which actually does what it's supposed to.
Layer 6a: CDAs
Layers 6a through 6e could really be five distinct layers, but it's easier to lump them together as the P-and-T layer with sublayers. Like any layer, you apply CDAs first – that's layer 6a!
Example: Traproot Kami sat like a Wall.
Prismatic Omen gives your lands types all.
Since type-change effects are back in layer 4,
Traproot Kami's toughness goes up some more.
Layer 6b: Other Power/Toughness Stuff
Wait, how is the second P/T layer the catch-all?! Like I said earlier, this produces the most intuitive results. Only two things actually fall in here, so remembering them might be easier:
- Effects from resolving spells and abilities (Giant Growth)
- Effects that set power and/or toughness (Humility again!)
Example: Brad controls Opalescence and Humility because he wants to be like Sheldon. Both set power and toughness, and neither p/t-setting effect is dependent on the other, so they're applied in timestamp order. Whichever came into play last "wins," and its effect will determine Humility's power and toughness.
Example: Janet tosses a Giant Growth on her Ancient Ooze, and then Frankie Humbles it. First Ancient Ooze uses its CDA to make its power and toughness large, then Giant Growth makes it +3/+3, but Humble's latest timestamp wins out and this Ooze is merely 0/1.
Example: Rocky runs in and Invigorates Janet's Ancient Ooze from the above example. We're still on timestamps here – it will be applied after Humble, and the Ooze will end up as 4/5. (No existing effects in all of Magic create dependency in the power/toughness layers – anything you run into within a single layer will pure timestamp.)
Layer 6c: Counters
Yay, another easy layer! Counters apply here. That's it.
Example: Mary has a little lamb. It gets Ovinized and becomes . . . well . . . a grown-up sheep instead of just a lamb. But since it has a +1/+1 counter on it, it's now 1/2 instead of just 0/1.
Example: Because the other children laughed at her lamb, Mary put a -1/-1 counter on each of them, then summoned a Godhead of Awe. Godhead of Awe made them all 1/1 in layer 6b, and in layer 6c, their counters made them all die. Mary was taken down by a police S.W.A.T. team sniper two hours later. Godhead of Awe pled insanity due to having only one hideous eye and went on to form a support group for the ocularly challenged. Mary's lamb remains at large.
Layer 6d: Static Plus and Minus
This layer is for any static abilities that give pluses or minuses to power and/or toughness, such as Glorious Anthem, Giant Strength, and Immolation. Pretty easy – you just have to remember to keep these separate from layer 6b when going through timestamps.
Example: Anthony has a Pirate Ship with a Heartseeker equipped. Johanna Humbles his Ship. Humble makes it 0/1 in layer 6b, but Heartseeker brings it back to 2/2 in layer 6d.
Example: Lucy has an Inkfathom Witch with Helm of the Ghastlord on. It goes unblocked, so she uses the Witch's ability to make it 4/1. Once again, this setting applies in layer 6b, while the Aura's pump applies in layer 6d, so she has a 6/3 Witch.
Example: Nellie has a little Marble Priest with a -1/-1 counter on it. But she also has a Glorious Anthem and Humility. In layer 6b, the Priest becomes 1/1; in layer 6c, it becomes 0/0. State-based effects won't be checked in the middle of applying layers, though, so it'll go back up to 1/1 in time to survive.
Layer 6e: Switches
And last but not least, effects that switch a creature's power and toughness. This is the very last effect due to an ancient precedent: cards originally said "Further effects that affect this creature's power affect its toughness and vice versa." That rider on switch effects was stripped from the cards and stuck into the rules, and here it is. It's vital to remember that this is last, and does not follow timestamps when looking at layer 6b.
Example: Charlie plays Aquamoeba's power-and-toughness switch ability. After it resolves, Grahame splashes it with Torpor Dust. Even though Torpor Dust resolved last, it must be applied before the switch: Aquamoeba is a -2/3 creature, then a 3/-2, and then it dies a messy death.
Layers 7 & 8: The Forgotten Layers
7 and 8? Who ever talks about layer 7 and layer 8? No one, hence they are the "Forgotten Layers." Layers 1 through 6 concern themselves with continuous effects that affect objects, but 7 and 8 are continuous effects that affect non-objects, such as players and game rules, so they don't even really fit in with the first six layers. You can generally forget about them and just worry about the effects as they come; I'm only including them here for the sake of completeness.
Layer 7 is the player layer. Isn't that fun to say? Player layer player layer player layer. To date, Seht's Tiger and a handful of "you have/gain shroud" cards are the only cards with effects that apply in this layer, so there isn't much to give in the way of an interaction example.
Layer 8 is the game-rule layer. It's not as much fun to say as player layer, but it's hugely important. This is where you apply such wonderful things as Spellbook, Rule of Law, and Ballyrush Banneret. Some of the effects that fall in here are subject to other rules ordering them, such as the "plus, minus, set" order for spell-cost modification, but most effects here follow the timestamp rule. (Dependency is so rare here as to be nonexistent, but it would be taken into consideration if two effects did create dependency.)
Example: Jack controls Spellbook and plays Null Profusion. Since Null Profusion's effect started later, it "wins," and Jack's hand size is two.
Example: Jill controls Sphere of Resistance, Trinisphere, and six other artifacts. She wants to play Myr Enforcer. For continuous effects affecting the cost of spells, first you apply any additions, then any subtractions, and then any effects that set the cost to a certain amount. First Sphere of Resistance adds to the cost to raise it to , then affinity reduces the cost by to , but then Trinisphere sets it back to . The final amount she must pay is .
Good, You Get It
The layer system is a lot to digest. If you haven't already been exposed to and studied it, you'll need to reread this article a couple more times to fully grasp it. If it's still a confusing mess of words, don't feel too bad; it's one of the trickiest parts of the rules to master. But once you're comfortable with this system, hundreds of common rules questions and absurdly complex rules puzzles suddenly become easy as pie!
Your homework: Post layer-interaction situations in the forum for the other readers to solve.
Until next time, have fun with onions!
- Eli Shiffrin