I thought I'd bring this over here from the Daemon Prince thread in the general forum.

The question is, when you declare multiple attackers or defenders, do you declare them all at once, and then get to the constant / forced effects they each might have triggered, or do you declare unit A, resolve constant / forced effects triggered by this, then declare unit B, and so on.

I've just submitted a Rules Question so we get an official answer, but I think it is safe to say you declare them all at once. I've had this discussion in the past, and the arguments that were made for one by one were mainly that constant / forced effects don't have to wait for an action window, and the FAQ's wording on Counterstrike ("Counterstrike ... allows a unit do immediately damage an attacker whenever it is declared as a defender").

However, rules and FAQ only ever say you "declare attackers / defenders", they don't break these steps down into smaller ones, and neither the rules on constant / forced effects nor the Counterstrike wording, while ambiguous, clearly contradict that you declare all defenders at once. Also, let's look at Friedrich Hemmler (Forced: When this unit is opposed in combat, deal 1 uncancellable damage to each attacker and each defender.). If you declare individually, he'll only ever damage one defending unit when he attacks, the first one that is declared, or just himself on your side when he defends. I don't think this is the way the card was intended, or that anyone actually plays it that way.

Thoughts?

I think your interpretation will be right, but I really can't think of any precedent to point to. I view the declare attackers/defenders steps as similar to applying combat damage. You do it all, then you look to see how many different things triggered and resolve them according to the flowchart. I think your reasoning about Hemmler is good as well.

From Lukas: You declare attackers and defenders all at once. After they have been declared you will trigger any Constant or Forced effects resulting from this, and then an Action window opens. So if there is a unit with Counterstrike, then he is declared simultaneously with all other units, and then the keyword triggers.

What happens if Descendant of Indraugnir attacks and there is a defendant with Duelist Training attached? Does the action on the Descendant of Indraugnir come into effect first? So he's declared attacker, an opponent's unit defender and then 4 indirect damage points are applied before the Counterstrike?

First you declare your attackers (including indraugnir) then there is an action window in which you can deal indirect damage.

After that, defenders are declared and counterstrike takes effect (and thus can kill indraugnir).