Step By Step: Declaring Attackers

Instructing your minions to savagely maul your opponent is a surprisingly complicated process. The comprehensive rules divides it into 12 steps, several of which are surprisingly involved. The steps in the CR are not the best way to present the process, so for the purposes of this article I'll reorganize and simplify them down to 7 steps.There's no functional difference between the CR's process and mine, it's just an alternative way of explaining the same actions. These steps are as follows:

  1. Choose our attackers.
  2. Check for restrictions.
  3. Check for requirements.
  4. Tap the creatures.
  5. Determine the total cost to attack.
  6. Activate mana abilities.
  7. Pay all costs to attack.

As usual when a single game process is broken down into multiple steps, we just take each step on its own one at a time, and if it ever turns out that one of the steps can't be legally followed, the whole process is illegal and we treat it as though it never happened.You're probably more used to seeing that process used for casting spells, but it functions exactly the same here.

A brief note: This is a more advanced article intended for people who already have a strong grasp of the rules around the combat phase, paying costs, and mana abilities. If you find it overwhelming, it may help to read a primer on those first.

Step 1: Choose our attackers

Here we select which creatures are going to attack. We also specify what they're going to be attacking (either an opponent or an opponent's planeswalker), and whether they're in any bands. The creatures have to be untapped and we must have controlled them since the turn began. Creatures in a band have to all be attacking the same player or planeswalker.Note that whenever this article mentions multiplayer, I'm going to be assuming that you're playing with the "attack multiple players" option. Technically the default rules for multiplayer only allow you to attack one player, but I have yet to come across a playgroup that plays that way. Also, for most other portions of the article, I'm going to assume we're talking about a two-player game with no planeswalkers. Technically every time I talk about a "set of attackers" I should be talking about a "set of attack declarations", since there could be multiple choices for what a single creature is attacking. But it's simpler to avoid that while explaining the concepts, since they can all be easily generalized to multiplayer.

Step 2: Check for restrictions

Next we need to make sure that our set of attackers doesn't violate any restrictions. A restriction is any effect that could directly prevent a creature from attacking. For example, defender, "this creature can't attack alone", or "no more than one creature can attack each combat".

All restrictions must be satisfied in order for a set of attackers to be legal; we can never have a creature attacking in violation of any restriction. If your chosen set of attackers violates any restrictions, it's illegal.

Restrictions can also come from costs, like "this creature can't attack unless you sacrifice a land", or "Creatures can’t attack you unless their controller pays {2} for each creature they control that’s attacking you." For any costs that you're planning on paying, you ignore their restrictions.I'll elaborate on this down in step 5.

Step 3: Check for requirements

We also have to look at any requirements that apply to our creatures. A requirement is any effect that directly requires a creature to attack, perhaps only under certain conditions. For example, "this creature attacks each combat if able", "at least 1 creature attacks each combat if able", or "if any creature attacks, all creatures attack if able".In almost all situations, all restrictions are always satisfied if nothing attacks, and all requirements are always satisfied if everything attacks. The only exception so far is Nacatl War-Pride. (Well, that's a blocking requirement, not an attacking one, but they work the same way.)

Sometimes it won't be possible to satisfy all requirements without violating any restrictions, so we only have to satisfy as many as we can. In other words, out of all possible sets of attackers that don't violate any restrictions, you have to attack with a set that satisfies the maximum possible number of requirements.

Let's look at an example. You control Crazed Goblin, Avatar of Slaughter, Bear Cub, and Wall of Roots. Your opponent controls Crawlspace. Ignoring all requirements and restrictions, there are 16 possible sets of attackers:Each creature can either attack or not attack, meaning that there are 2 options for each creature. So the total number of options is 2^N, where N is the number of creatures you control.

Attacking with Wall of Roots violates its restriction, and attacking with any more than 2 creatures violates Crawlspace's restriction. It's never legal to violate restrictions, so we can remove all those options from consideration. We're left with 7 sets of attackers that comply with all restrictions:

Next we count up how many requirements are satisfied by each option:

The greatest number of requirements that can be satisfied is 3, so we must pick either of those two options. We must attack with Crazed Goblin and 1 other creature; either Avatar of Slaughter or Bear Cub.

Seems simple enough, right? Well, there are a few complications.

Complication #1

The astute among you may have noticed that the previous few paragraphs contradicted each other. I said that a combat requirement is a type of effect. Avatar of Slaughter creates one continuous effect. Therefore it creates one requirement. That requirement is satisfied if all creatures attack, and is not satisfied otherwise. This would mean that in the example scenario above, you'd be able to attack with only Crazed Goblin and no other creatures.

This is indeed what's written in the CR508.1d tells us that a requirement is "an effect that says a creature attacks if able, or that it attacks if some condition is met"., but it's an error. Wizards of the Coast apparently forgot their own definition of the term "effect" when they were writing the rule on combat requirements, and assumed that the number of effects Avatar of Slaughter creates is dependent on the number of creatures on the battlefield. (Or perhaps they just forgot that cards like Avatar of Slaughter existed.) Extrapolating from various official rulings they've issued over the years, and the fact that treating it any other way would lead to some very unintuitive results, I'm confident that their intention is that Avatar of Slaughter creates a separate requirement for each creature on the battlefield.Slightly concerningly, this Cranial Insertion article claims that War's Toll only creates a single requirement, and that if you're unable to attack with all of your creatures it isn't satisfied at all. Cranial Insertion is usually a pretty reliable source, but considering that their explanation would mean that an opponent simply controlling a Wall of Roots would render War's Toll's effect useless, I think it's safe to say that Cranial Insertion just got this one wrong. The rest of this article will operate under that modification of the rules.

Complication #2

Aren't we ignoring some important words here? Avatar of Slaughter says "if able", and a creature with defender isn't able to attack. Avatar of Slaughter's requirement should be satisfied even if some creatures don't attack, as long as they weren't able to attack in the first place.

But this only helps if we can determine whether each creature is "able to attack" without knowing what requirements need to be followed, which we can't do.

The simplest definition would be to define "ableness" to mean something like "has been on the battlefield since the beginning of the turn and doesn't have defender". But by calling out defender in particular, it would get treated differently from some other restriction. Clearly if you control Scarred Puma and no black or green creatures, it shouldn't work differently from controlling a Wall of Roots. So that's no good.

Ok, how about we expand the definition to include any creature with any restriction that renders it unable to attack? But now that's ambiguous. If you control Silent Arbiter and Bear Cub, which creature is "able to attack"? Both? Neither? It's unclear. The problem isn't limited to non-local restrictions like Silent Arbiter; if you control two Master of Cruelties, we have the same problem.

We can resolve that ambiguity by saying that a creature is "able to attack" if there's any set of attackers that is legal after step 2 and includes that creature. But now we can end up with a set of creatures that are each individually "able to attack", but they can't all attack! If you control Silent Arbiter and Avatar of Slaughter, they're both "able to attack" under this definition, yet you can't choose both as attackers, so we're right back where we started: Avatar of Slaughter's requirement cannot be satisfied no matter what you do, so it's legal to attack with no creatures. This interpretation is no good.

It would be tempting to say that a creature is "able to attack" if there are any legal (after taking requirements into account) sets of attackers that include it, but now our definition is circular! In order to know what the legal sets of attacks are, we'd have to know which creatures are able to attack. But in order to know which creatures are able to attack, we'd have to know all the legal sets of attackers. This is obviously unhelpful.

Any comprehensive and unambiguous definition of "ableness" would have to rely on a process similar to what we're already doing, where we compare multiple sets of potential attackers in order to determine which creatures are "able" to attack under certain conditions. This means that pointing at the phrase "if able" doesn't add any explanatory power, and since every attack requirement has the "if able" disclaimerSome use slightly different wording, like Prized Unicorn, but it's the same concept., we may as well ignore it entirely.

This is also something that Wizards forgot to put in the CR, but again I'm confident that this is their intention; after all, if we were supposed to figure out which creatures are able to attack and requirements only applied to those creatures, then there would be no need for the rule that talks about maximizing the number of requirements fulfilled, because you could always fulfill all requirements! So it's pretty clear that we're supposed to just ignore anything that talks about whether a creature is "able" to attack.This ruling on Judgeapps also backs that up, as does CR 506.6"Some abilities check to see whether or not a creature “had to attack” during a particular combat phase. A creature had to attack if one or more effects were requiring that creature to attack at the time attackers were declared in that combat. A creature did not “have to attack” if there were no such effects that required it to attack, even if there were no other legal attacks that could have been declared." by implication.Since if requirements didn't apply to creatures that weren't able to attack, it wouldn't make much sense to say they "had to attack" either.Notably, a lot of judge resources get this wrong, such as this rules tip. Some even contradict themselves in confusion, such as this rules tip and this Judge Academy article, by claiming that we are following the "if able" disclaimer yet still violating the requirement, somehow?

So to sum that up, whenever you're working with attack requirements, you should pretend that the "if able" part doesn't exist. The rest of this article will make that assumption as well.

Complication #3

You control Viashino Bey. What are your legal attacks?

That's right, you have to attack with Viashino Bey! Doing so satisfies 1 requirement, whereas not doing so satisfies 0.

Um.

Yeah, so there's a specific class of requirement that doesn't work at all under the rules- any requirement that only exists for some sets of attackers and not others. I call these conditional requirements. I think Wizards didn't bother to consider them when writing the rules, because there are only 4 cards with this type of requirement: Viashino Bey, War's Toll, Ekundu Cyclops, and Magnetic Web.This is a little surprising, since War's Toll was in a Commander deck and actually sees some play.

I have been unable to find a single official ruling that even touches on how these are supposed to work, nor do any other judge resources try to explain it.Except this Cranial Insertion article from 2006, which was written back when the intended result of combat requirements and restrictions was very different, and is therefore unhelpful. So, we need to make up a system from scratch that matches our intuition of how these cards should work.

If you're someone who enjoys thinking about rules design, I'd encourage you to pause here and try to figure out a solution. You'll learn a lot more by working through it yourself than you will from just reading my description, and it's quite a fun challenge. If you'd like to get a hint or to ask a specific question without seeing the whole answer, feel free to make a comment down below, or ask me directly. Whenever you're ready, open the next section.

This was quite a challenge. I spent more than two months brainstorming on this, and every idea had some flaw; some board state where the system gave one answer and intuition gave another.If you're curious to see some of the systems that didn't work, I've compiled 28 of the attempts I could remember into this spreadsheet.

Eventually, with considerable help from Arjen Baarsma - a mathematician and Magic player I met a few years ago - we did it. We found a simple system that (as far as we know) returns the intuitive result no matter what the board state is.With one frustrating exception that can only occur with hypothetical cards. Since it's unlikely that Wizards will print any more conditional requirements, I decided to not worry about it. That said, if anyone has an idea for an even better system that solves this problem too, I'd love to hear about it. It works like this:

Conditional requirements can either be "on" or "off". If Viashino Bey isn't attacking, its conditional requirement is off, and it doesn't count towards the number of requirements that exist. If it is attacking, then it's "on", and it creates 1 requirement for each creature you control.

You start by considering what requirements currently exist, assuming you've chosen no attackers. You choose a set of attackers that satisfies the maximum number of those requirements. Then you check again to see what requirements exist for that set of attackers. Then you choose a new set of attackers that maximizes those requirements. Continue repeating this process until the new set of attackers is one you've chosen before. And while you're going through these steps, you only consider new sets of attackers that don't satisfy any fewer of the requirements from previous steps.

Let's look at some examples. First off, the simple case where there are no conditional requirements. You control Bear Cub and Crazed Goblin. How does this process work here?

You start off by considering the empty set of attackers. You check to see what requirements exist for that set and it's just one: Crazed Goblin's. Next you choose any set of attackers that satisfies the maximum number of requirements: that can be either Crazed Goblin on its own or Crazed Goblin along with Bear Cu