Published on 04/18/2005

Who's Afraid of Continuous Effects?

Cranial Translation
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Note: This article is over two years old. Information in this article may be out of date due to subsequent Oracle and/or rules changes. Proceed with caution.

Hello everyone, and welcome to the fourth installment of Cranial Insertion, your weekly rules column! This week we'll be taking a somewhat different approach from other weeks. Instead of answering a number of questions on several different topics, we'll discuss a single topic more in-depth. The topic for today is the interaction of continuous effects.

Q: I have Humility and two copies of Opalescence in my graveyard, and I play Replenish. What happens?

A: *silence*

It's clear Moko doesn't like me. :( He obviously knows that continuous effects are one of the most despised parts of the Magic rules. The mere mention of Humility and Opalescence in the same question is often enough to fill the heart of any rules guru with terror. I'll bake Moko a cake to let him know I mean well. Maybe then he'll let me answer some easy questions in the future. :)

Before we begin, let's have a look at what we're going to talk about in the first place. Most of what will be covered here can be read in the Comprehensive Rulebook under rule 418.

An effect is the general term for what happens when a spell or (activated or triggered) ability resolves. There are two main types of effects: one-shot effects and continuous effects. A one-shot effect causes something to happen immediately. After it has been applied, it no longer affects the game. Shock and Terror are examples of spells that create one-shot effects.

Here's a continuous effect that
likes to mess with the rules
Continuous effects are different: they stick around and affect the game for a certain period of time. This period may be something like the duration of a single turn, but it may also be for the rest of the game. Examples include Giant Growth and Blessed Breath. Continuous effects can also be generated by static abilities: this is what cards like Night of Souls' Betrayal and Mirror Gallery do.

(Other types of effects are replacement effects and prevention effects. Such effects are special cases of continuous effects. You may have heard about state-based effects, too. Those are not created by spells or abilities, but by the rules of the game.)

Having a bunch of continuous effects all active at the same time can be quite a headache. It may sometimes be very unclear what the result will be when several continuous effects are combined. To figure out what happens in any given situation, the rules describe a procedure that will lead us to the answer.

If at any point during the game you want to know what the game state looks like, you can find the answer as follows. First, forget about continuous effects and look at all the cards as they are printed. In the case of tokens or face-down cards, instead use the information given by the effect or the rule that created the token or face-down card. Next, apply all the continuous effects one after the other. After all effects have been applied, you'll have found the current game state. The difficulty is, of course: what order are the effects applied in? This is the main subject of the Comprehensive Rulebook on this topic (see rule 418.5. Interaction of Continuous Effects).

There are three factors that determine the order in which continuous effects are applied. They are layers, dependency, and timestamp. I'll go through them one by one. The order they are listed in is relevant. Layers are listed first because they're the most important in the sense that if the layer rules tell you that one effect should be applied before another, then the dependency and timestamp rules can't change that. Timestamp is the least important in the same sense: the timestamp rules only matter if the layer and dependency rules couldn't tell you which effect to apply first.


The rules for layers are quite straightforward, but they are one of the few things in the Magic rules that require memorization. The layers are as follows (see rule 418.5a):

  1. copy effects;
  2. control-changing effects;
  3. text-changing effects;
  4. type-, subtype-, and supertype-changing effects;
  5. all other continuous effects, except those that change power or toughness;
  6. power- or toughness-changing effects.

If two effects fall in different layers, then they are always applied in the order of those layers.

Q: I control a White Knight and a Crusade. My opponent used Mind Bend to make my Crusade affect black creatures instead of white ones. I changed my White Knight's color to black using Blind Seer. How big is my Knight?

A: Start with the Knight's printed value of 2/2. Now we need to figure out which layer each of the effects belongs to. Crusade wants to change power or toughness (both, in fact), so it has to wait until layer 6. Mind Bend changes text, so it goes in layer 3. The continuous effect created by Blind Seer's ability falls in the "miscellaneous" layer 5. Now we apply them one by one. Mind Bend goes first, so Crusade is changed to read "Black creatures get +1/+1." Next up is Blind Seer, which colors the Knight black. Finally, Crusade is applied: it looks for all black creatures and sees that the White Knight is one of those, so it gives it a +1/+1 bonus. End result: the Knight is 3/3.

As you can see, the layers cause things to work just the way you'd expect them to work. At least in this case...

Sometimes, it isn't clear what layer an effect belongs to, because it may do several different things that would make it go in different layers. In such a case, the effect is split up, and each part is applied in its own layer. There is one exception to this: if some part of the effect changes type, subtype, or supertype, which would make it fall in layer 4, then the entire effect goes in layer 4.

What layer are you in?
Q: I have a Forest with Genju of the Cedars on it. My opponent uses Blind Seer to make my Forest black. I activate my Genju, animating my Forest. What color is it?

A: The Genju's effect modifies the Forest's type to be a creature land, and its subtype to be a Spirit. That means that the entire effect (including the color-changing and P/T-changing parts) falls in layer 4, where it is applied before Blind Seer's effect from layer 5. First, the Genju makes your Forest into a 4/4 green Spirit creature land. Then Blind Seer makes it black instead of green.

So, what happens if two effects fall in the same layer? The layer rules still have something to say about that: if one of the effects is from a characteristic-setting ability, then it goes before any other effects. A characteristic-setting ability is an ability that assigns a value to one or more of the characteristics of the object the ability is on. Examples of cards with characteristic-setting abilities are Crimson Kobolds, Kodama of the Center Tree (both its abilities), and Mistform Ultimus. Note that an ability which determines the value of a characteristic for another object is not a characteristic-setting ability!

Oh, and there's also counters that modify power and toughness. Those are applied in layer 6, after the characteristic-setting effects, but before the normal effects.

Q: I control Kodama of the Center Tree but no other Spirits. Then my opponent activates Imagecrafter to change my Kodama into a Pyknite, which would make it 0/0. I respond to the Imagecrafter's ability by playing Kodama's Might. Will my Kodama survive?

A: After the Imagecrafter's ability resolves, there'll be three continuous effects to deal with: one from Imagecrafter, one from the Kodama itself, and one from its Might. Imagecrafter's effect is the only one from layer 4, so it goes first. The other two belong in layer 5, but the Kodama's effect is characteristic-setting, so it gets to go before the Might. It makes the Kodama 0/0, then the Might makes it 2/2. Note that the Kodama was never actually 0/0 as far as the game is concerned. The 0/0 appeared as an intermediate result during the calculation of the continuous effects. Other parts of the game don't care about intermediate results, only about the final result. So the Kodama will survive.

When the turn is over, both the Imagecrafter's and the Might's effect will end at the same moment, leaving the Kodama at 1/1 again.


It will often happen that the layer rules can't tell you which effect goes first, because the effects you're looking at would all fall in the same layer and none of them are characteristic-setting effects. In such a case, the dependency rules are next in line to provide an answer.

So, what can the dependency rules tell us?
From the CompRules:
418.5c An effect is said to "depend on" another if (a) it is applied in the same layer as the other effect (see rule 418.5a) and (b) applying the other would change the text or the existence of the first effect, what it applies to, or what it does to any of the things it applies to. Otherwise, the effect is considered to be independent of the other effect.
The first condition (a) is obvious: if the two effects don't fall in the same layer, then we already know which should be applied first, and we don't need the dependency rules. Condition (b) says, in short: effect A depends on effect B if applying effect B first would change what effect A does.

If you have two effects A and B, and effect A depends on effect B, then effect B will be applied first. If A and B don't depend on each other, then we move on to the timestamp rules.

This rule may still lead to confusion if a number of effects form a circle, and each effect depends on the next in the circle. According to the rule, you'd have to apply all of them first, which would be rather hard to accompish. In that case, we also refer to the timestamp rules.

Q: I have a Forest enchanted with Genju of the Cedars. I also control a Conspiracy which changes all my creatures, creature spells and creature cards to have subtype Monkey. When I activate my Genju, what creature type will my animated Forest be?

A: Both effects we are dealing with fall in layer 4, so we have to resort to the dependency rules. Let's see what the dependencies between the two effects are. Applying Conspiracy before the Genju doesn't change what the Genju does: the Genju's effect will just animate the land and make it a Spirit. So Genju doesn't depend on Conspiracy. However, applying Genju before Conspiracy would change what Conspiracy applies to: it will only affect the Forest in question if it has been changed into a creature. Conspiracy depends on the Genju's effect, so the Genju's effect is applied first, creating a Spirit creature. Then Conspiracy will come along and change the Spirit into a Monkey.

Q: I control a White Knight. My opponent Mind Bends it to change its protection from black to white. I play my own Mind Bend to change all instances of white to black again. Does this cause an infinite loop?

A: No. Continuous effects never end up in infinite loops. The rules described here place each effect somewhere in a sequence, and each effect will only occur once in that sequence. In this case, both effects fall in the same layer, but your effect depends on your opponent's (because yours wouldn't do anything unless your opponent's effect changed the Knight's protection to white first) while his doesn't depend on yours. That means that his effect is applied first (now pro-white), followed by yours (pro-black again).


If all else fails, we look to the timestamp rules to tell us in what order to apply the effects. These rules will always be able to provide an answer, so we won't have to look for a fourth set of rules. Yes, we're approaching the end of this article. :)

First, what is timestamp? Each object is given a "timestamp" when it goes to a new zone. For example, when you play a creature, the creature spell first goes from your hand to the stack, where the creature spell receives a timestamp. Then, when the spell resolves, the creature comes into play, and gets a new timestamp again. These timestamps are used to determine in what order different things entered their zones.

When two objects change zones at the same time, for example a number of creatures coming into play simultaneously through Patriarch's Bidding, then the active player gets to choose the order in which they are timestamped. Note that this doesn't mean that they change zones at different times: they still move together, but they all need a different timestamp despite that fact.

When you use the timestamp rules to see which of two effects is applied first, the result is as follows: the effects are applied in timestamp order. For a continuous effect from a static ability, use the timestamp from the object the ability is on. A continuous effect from a spell or (activated or triggered) ability gets a timestamp when the effect is created.

Setting P/T to 0/2 since 1993
Q: I play Giant Growth on my Grizzly Bears, then my opponent uses Sorceress Queen on my Bears. How big are they?

A: Both effects are P/T-modifiers from the sixth layer, and neither depends on the other, so it comes down to the timestamp rules. The Giant Growth has the earliest timestamp, so it's applied first, making the Bears 5/5. Then, Sorceress Queen's effect makes it 0/2, overwriting the effect of the Giant Growth. Remember that Sorceress Queen's effect isn't a characteristic-setting effect, because it modifies the characteristics of another object.

There are two exceptions to the above rules for assigning timestamps. First, a permanent that phases out and back in keeps its old timestamp. That's because phasing is weird. :rolleyes: The other exception is more relevant: a local enchantment or Equipment that becomes attached to a different permanent also receives a new timestamp at that moment. This ensures that the enchantment or Equipment will always have a later timestamp than the thing it's attached to.

Q: I control Slagwurm Armor and Aquamoeba. I play Aquamoeba's ability and let it resolve. Then I use the Armor's equip ability to attach it to the Aquamoeba.

A: The Armor's effect gets a timestamp when the Armor is moved on the Aquamoeba, while the Aquamoeba's effect's timestamp was made when the ability resolved. So the P/T-switching ability will be applied first, making the creature 3/1. Then it gets the +0/+6 bonus from the armor, resulting in a 3/7 Aquamoeba.

Q: When the turn ends, the P/T-changing effect wears off, but the Equipment remains where it is. What happens now?

A: We start from the beginning with a 1/3 Aquamoeba. There's only one effect to apply: the Armor's bonus. The Aquamoeba will be 1/9. Be careful and don't try to undo the P/T switching effect by simply switching back the P/T. That would give you a 7/3 Aquamoeba, which is incorrect.

Q: What if I equip the Armor on the Aquamoeba first, and then switch the Aquamoeba's power and toughness?

A: Now the timestamps are the other way around. Apply the +0/+6 first for a 1/9 Aquamoeba, then switch the power and toughness to end up with a 9/1 creature.

Ach! Hans, run! It's Humility and Opalescence!

Q: I have Humility and two copies of Opalescence in my graveyard, and I play Replenish. What happens?

A: We can now answer this question safely. Actually, we could have done it a lot earlier, because we only need the layer rules. Humility's effect (according to the current Oracle text) does two things: it removes abilities from creatures, and it gives an ability to itself. Both these things are miscellaneous stuff and belong in layer 5. (Yes, an effect that gives another object some ability listed between quotation marks is just giving the ability. It's not actually changing text, so it doesn't belong in layer 3.) The ability Humility gives to itself will change the power and toughness of creatures, so it goes to layer 6. Opalescence's effect also does several things, but because one of those things is changing types, the entire thing falls in layer 4.

The answer is now obvious: The Opalescences go first, changing all enchantments (including each other) into creatures of various sizes and with their original abilities. Then, in layer 5, all those abilities are removed except for the new ability on Humility. Finally, in layer 6, all creatures become 1/1.

This question used to be a lot more confusing under older versions of the rules and older versions of the card wordings, where it came down to the timestamp order that was assigned when the three enchantments came into play.

For continuity's sake, I'll be sending Moko back over the Atlantic. On a first class catapult volley, obviously. He seems to like the cake I baked, so he'll bring it along. Being a Zombie, he hasn't shown any interest in actually eating it yet. :rolleyes: If all goes well, next week Moko will be back to helping Eli select from the questions you send him, so keep them coming.

Until next time, may you be able to divide all your complicated problems into simple, transparent layers!

-Thijs van Ommen, The Netherlands

About the Author:
Even though I'm not a judge, my interest in the rules of the game is the main reason for me to play. You'll usually find me answering questions in the rulings forum. I'm mostly a casual player: the only tournaments I visit are prereleases.


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