I asked because it seems like the distinction between an acknowledged ‘no impact’ scenario (spell can't be cast from exile because it was “processed”) and the OP's example which isn't ‘no impact’ (spell can't be cast from exile because no legal targets) is a very hazy distinction to me, and this was my best attempt at stating a principle that could be applied to other situations. If there's a better way to understand the distinction, I would love to hear it, as I've been struggling (and failing) to understand this ruling in light of how I understand the rest of the MT policy.

What if… when i ask Ap “why didn't you tell NAP that he could cast Declaration in stone ?” and he answers me “There wasn't any other creature on the battlefield so DiS couldn't be cast, i didn't think it was important to point it out” ?

Is it still considered a missed trigger ?

By the book (and the O answer), it's a missed trigger and opponent can put the trigger in the stack and cast in DiS targeting Ormendhal, but as judges, we need to ask a few questions when a detrimental missed trigger occurs and the first question i always ask is “Why ?”
If Ap gives me the answer mentioned above, i'll never ever ask him to put his trigger on the stack. If he says “i forgot it”, then i'll ask his opponent if he wants to put the trigger on the stack (and i will feel very sorry for Ap).

This not pointing out the Spell Queller trigger seems to have deviated a bit into constructed ambiguity. If I may suggest a recommended fix for judges to suggest to players:

1) If there is no indication that the trigger was remembered, then treat it as missed. However, since there is a possibility that the players mutually understand that there is no “meaningful effect” of the trigger, so I wouldn't step in either. This is based on the “If the players can work it out for themselves, they don't need you to step in” clause (I don't remember where such a clause is located in the documents, but I recall discussion of it being added a couple months back).

2) If a player forgot their own detrimental trigger (or appeared to forget it by not making mention), treat it as missing a detrimental trigger normally, even if it creates weirdness. As Uncle Scott said, it's the player's responsibility to remember their own trigger. If they forgot, then whatever happens next is their own problem.

3) Regarding triggers that “don't do anything”, as in this scenario, where the trigger itself does something that creates a batch of actions where the batch would result in no change to the game state, what I do when playing is I would say something like “My Spell Queller dies, trigger goes on the stack, but there's nothing to target with the DecStone, so it stays in exile, ok?” and move on. This a) confirms that I remembered my trigger, b) confirms with my opponent that they have the option to cast their spell, c) confirms the game state at the moment, and d) confirms the end result of the batch of actions that started with my Spell Queller dying. While I feel that something like “Spell Queller dies, would you like to cast your DecStone onto the empty board *trollface.jpg*” is a bit over the top, I think something like the statement above is reasonable to expect players to remember.

Edited Lyle Waldman (Jan. 16, 2017 10:22:44 AM)

For those who are having difficulty swallowing Scott's answer, I think we should recall one of the first posts in this thread:

Originally posted by Philip Böhm:

Does it matter that Spell Queller's triggered ability has no targetting restrictions ? One could flash a creature into battlefield in response to the (announced) Spell Queller trigger. I do not agree with “the trigger wouldnt have an effect on the game”, because that assumption takes more future into account.

In this situation, the owner of DecStone has a choice when Spell Queller's trigger goes on the stack: to flash in a creature or not? This is distinctly a choice which affects the ability to cast DecStone, and requires someone to acknowledge Spell Queller's trigger.

Originally posted by David Poon:

In this situation, the owner of DecStone has a choice when Spell Queller's trigger goes on the stack: to flash in a creature or not? This is distinctly a choice which affects the ability to cast DecStone, and requires someone to acknowledge Spell Queller's trigger.

There is the same possibility with a trigger that would make the opponent sacrifice a creature (maybe they want to enable revolt). Any trigger opens new lines of play. We cannot rely on formal rules to decide whether a trigger has an impact or not: we have to decide what is reasonable and what is not.

Edited Florian Horn (Jan. 20, 2017 06:57:09 PM)

Originally posted by Bartłomiej Wieszok:

You are the HJ of PPTQ.
Andrew control Westvale Abbey, four Bear Cubs, and a Spell Queller with Declaration in Stone exiled with it. Andrew announces and resolves second ability of Abbey sacrificing all his creatures, including Spell Queller, but forgets to announce LTB trigger.
After Ormendahl, Profane Prince shows up on the battlefield, Norman calls you to the table and says:
N: “Judge, my opponent forgot about LTB trigger, I would like to resolve it now.”
Norbert also says, that he was aware of this trigger at the appropriate time and he waited on purpose with calling a judge.
What do you do?

Colleagues, acknowledging that an {O}fficial answer has been given, I had some questions of philosophy:

The Missed Trigger section in the IPG says “The opponent’s benefit is in not having to point out triggered abilities, although this does not mean that they can cause triggers to be missed.” It does not say either way when an opponent can/should point out a Missed Trigger.

Compare this to the philosophy in FTMGS which says "A player allows another player in the game to commit a Game Play Error and does not point it out immediately. If a judge believes a player is intentionally not pointing out other players’ illegal actions, either for his or her own advantage, or in the hope of bringing it up at a more strategically advantageous time, they should consider an Unsporting Conduct — Cheating infraction. Not reminding an opponent about his or her triggered abilities is never Failure to Maintain Game State nor Cheating.“

Yes, it explicitly says that ”Not reminding an opponent about his or her triggered abilities is never Failure to Maintain Game State nor Cheating" but this sits badly with me when considered alongside "A player allows another player in the game to commit a Game Play Error and does not point it out immediately".

Acknowledging that this is a corner case, is being able to wait until it suits you to point out a Missed Trigger something we are happy with moving forward, or something we think should be tightened-up in the next iteration of the IPG?

Scenario A: NAP does not acknowledge the MT - no problem.
Scenario B: NAP does acknowledge the MT straight away - no problem.
Scenario C: NAP waits to acknowledge the MT until it gets them the optimal result - sits badly with me.

Edited Steve Ford (Jan. 21, 2017 01:20:54 AM)

So six years ago we had a policy that more closely fit this intent (needing to point out opponents triggers). The current policy has evolved over many iterations, and at this point it's evolved to a much better place. There are definitely horror stories from this era, and I think crafting missed trigger policy too cover this acknowledged corner case isn't worth it.

Originally posted by Steve Ford:

Originally posted by Bartłomiej Wieszok:

You are the HJ of PPTQ.
Andrew control Westvale Abbey, four Bear Cubs, and a Spell Queller with Declaration in Stone exiled with it. Andrew announces and resolves second ability of Abbey sacrificing all his creatures, including Spell Queller, but forgets to announce LTB trigger.
After Ormendahl, Profane Prince shows up on the battlefield, Norman calls you to the table and says:
N: “Judge, my opponent forgot about LTB trigger, I would like to resolve it now.”
Norbert also says, that he was aware of this trigger at the appropriate time and he waited on purpose with calling a judge.
What do you do?

Colleagues, acknowledging that an {O}fficial answer has been given, I had some questions of philosophy:

The Missed Trigger section in the IPG says “The opponent’s benefit is in not having to point out triggered abilities, although this does not mean that they can cause triggers to be missed.” It does not say either way when an opponent can/should point out a Missed Trigger.

Compare this to the philosophy in FTMGS which says "A player allows another player in the game to commit a Game Play Error and does not point it out immediately. If a judge believes a player is intentionally not pointing out other players’ illegal actions, either for his or her own advantage, or in the hope of bringing it up at a more strategically advantageous time, they should consider an Unsporting Conduct — Cheating infraction. Not reminding an opponent about his or her triggered abilities is never Failure to Maintain Game State nor Cheating.“

Yes, it explicitly says that ”Not reminding an opponent about his or her triggered abilities is never Failure to Maintain Game State nor Cheating" but this sits badly with me when considered alongside "A player allows another player in the game to commit a Game Play Error and does not point it out immediately".

Acknowledging that this is a corner case, is being able to wait until it suits you to point out a Missed Trigger something we are happy with moving forward, or something we think should be tightened-up in the next iteration of the IPG?

Scenario A: NAP does not acknowledge the MT - no problem.
Scenario B: NAP does acknowledge the MT straight away - no problem.
Scenario C: NAP waits to acknowledge the MT until it gets them the optimal result - sits badly with me.

Good point, Steve!

Perhaps it helps if you think about it this way: If an opponent misses a “generally non-detrimental” (“beneficial” for the remainder of this post because it makes more sense to think about it this way, although strictly speaking not necessarily always “beneficial”) trigger, there exists “no way” (in airquotes because generally but not always true, e.g. Dark Confidant) for the opponent to put it on the stack which would favor the opponent, and therefore it doesn't matter (we still give the opponent the option for cases like Dark Confidant, but more often than not the opponent will decline their option). Furthermore, there is no penalty for missing a beneficial trigger; the penalty is that you missed something that is good for you. However, with generally detrimental triggers, missing the trigger is beneficial (because the trigger is detrimental, so not having something detrimental happen is beneficial by definition) which is why we give a Warning. As an additional penalty, we allow the opponent to put the trigger on the stack if they like, to prevent dodging and simply “I'll take my Warning rather than <whatever effect>”; if the player wanted the effect to be put on the stack at the appropriate time, they should have played more tightly and remembered their triggers better, otherwise they might allow their opponent to put the trigger on the stack at a more opportune time.

As Steve put it, we do have our final, official answer on this. Speculation fueled by corner cases may be interesting, and makes for great after-event, adult-beverage-in-hand, conversations - I'm not sure that it will help people who scan this thread to understand the underlying principles of policy. Please consider the merits of your favorite corner case, before you post?

Originally posted by Steve Ford:

is being able to wait until it suits you to point out a Missed Trigger something we are happy with moving forward

Yes, in fact, it is. As SHiggins pointed out, we used to have a completely different policy re: Missed Triggers. In those dark ages, you had to help your forgetful opponents play better. We fixed that, but it took several iterations of MT policy to get to where we are - which is, honestly, a very good place to be (but by no means perfect in every one of those many, many corners).

d:^D