How does an Amulet of Proof against Detection and Location interact with the Augury spell?

Question

One of my players got his hand on an Amulet of Proof against Detection and Location, which hides him from divination magic. The description says:

While wearing this amulet, you are hidden from divination magic. You can't be targeted by such magic or perceived through magical scrying sensors.

Does the augury spell work on him? I would think that it would work on the party - but if the question is about an action he (and only he) is going to do, what happens? Does the god answer "Nothing" to the priest? Or is he not considered the target of the spell?

The auguries in question:

Currently, the question players are thinking of asking is about the thief (wearing his amulet) going solo in a dark cavern (he's got really good bonus to Stealth, Boots of Elvenkind, and the invisibility spell) to prepare an ambush.

The others will come a bit later, trying to attract attention so that the foes fall into the ambush (caltrops, hidden thief, and difficult terrain). Players don't know if the enemy has magical abilities that would lend to too much risks (answer is no).

There is a really good chance that their plan works. The problem is that its main actor is the thief, who is protected by the amulet. And the thief really doesn't want to remove the amulet, for a reason that the rest of the team doesn't know about.

Answer 1

Nothing

He is hidden from divination. Augury is divination. Thus, Augury can't perceive him and thus cannot provide any answers about him, or actions that include him as key part. If he would take the amulet for the time spell is being cast, and the question would be "I plan to put amulet on and then..." it would work.

But maybe?

There are two issues that make it DM discretion, one bad, one good for you:

1. Augury has range Self, and description "a specific course of action that you plan to take", so asking about whole party is iffy already. English does not have clear distinction between singular and plural "you", and range is singular.

2. It might be a valid question if asked in a form "I want to follow a rogue, assuming that he will not be perceived by normal or magical means" - Augury cannot perceive the rogue, but no rule forbids caster to make certain assumptions when casting this spell. No rule allows them, either - thus, it is DM ruling territory.

How would I rule

If question was about rogue, I would answer "Nothing" for two reasons, amulet and range of Augury. If, on the other hand, question was about caster doing things, and assuming rogue is not caught, I would give a honest answer, but answer that ignores any risks to the rogue herself: spell cannot perceive him, so spell must assume the same things caster assumes.

Ruling "Nothing" in all cases sounds reasonable too. Only straight out answer is against the rules.

Answer 2

A creature wearing the amulet would be hidden from an Augury spell cast by someone else.

The amulet of proof against detection and location protects the wearer from being located or surveilled through Divination magic. It also protects the wearer from being targeted by Divination spells.

A character who is wearing (and attuned to) the amulet is not the target of an augury spell if s/he is not the caster, but will still be hidden from the spell's magic, which may affect the outcome of the spell.

The outcome of augury is just one of four possible omens: "weal," "woe," "weal and woe," or "nothing." It would be up to the DM to adjudicate how the amulet would affect this outcome, depending on how strongly the amulet wearer figures into the question being asked. If the question involves the amulet wearer primarily, a result of "nothing" may be appropriate. If the question involves others as well, one of the other results may still be appropriate.

For your specific example:

Since the thief is hidden to the augury magic, the result you deliver should be based upon what would happen if the other characters entered the room and attracted the monsters' attention without the thief having gone in and laid traps first. This might result in an omen of "woe", while otherwise the result might have been "weal." Or, if the monsters are not much of a threat to begin with, the result might still be "weal."

If the caster is wearing the amulet:

For the sake of completeness, I will also note that a creature wearing (and attuned to) the amulet is unable to cast augury at all, as the target of the spell is "self." The spell would fail, as it would be unable to target the caster.

Answer 3

The answer to this is a bit more nuanced than a simple yes or no, as an Augury concerns a specific planned course of action rather than a question about an individual, and has four specific outcomes rather than specifically failing in some way.

The Augury spell description (PHB p. 215) says:

you receive an omen from an otherworldly entity about the results of a specific course of action that you plan to take within the next 30 minutes. The GM chooses from the following possible omens:

• Weal, for good results
• Woe, for bad results
• Weal and woe, for both good and bad results
• Nothing, for results that aren’t especially good or bad

The spell doesn’t take into account any possible circumstances that might change the outcome, such as the casting of additional spells or the loss or gain of a companion.

So the way this would play out is that the caster will outline a planned course of action and the GM will choose from one of the four outcomes not taking account of the change in circumstances represented by the existence of the character wearing the amulet, as they don't exist as far as the spell is concerned.

Some examples to illustrate this:

1. "We plan to kill X with a big magic flaming sword" where X is wearing the amulet. I would adjudicate a Nothing answer, as, as far as the Augury is concerned, nothing would happen as a result of the plan as the person does not exist, and so it is not good or bad.

2. "We plan to kill X with a big magic flaming sword" where X is personally vulnerable but has a really tough bodyguard wearing the amulet. I would adjudicate that the Augury would return a Weal answer as, ignoring the circumstances represented by the bodyguard who does not exist as far as the Augury is concerned, the killing should be easy.

3. "We plan to kill X by having Y run up to them and hitting them with a big magic flaming sword" where Y is wearing the amulet. I would adjudicate that Nothing would result as, as Y does not exist as far as the spell is concerned, the Augury will divine that nothing much will happen, which is not good or bad.

In all cases the GM simply ignores the change in circumstances represented by the person wearing the amulet, they simply do not exist, to work out the result of the Augury.

The specific scenario described in the question will ask if the plan to enter the cave in the manner described will work out well. You should answer as if the rogue does not exist, i.e. as if there is no ambush, no possibility the enemy will spot the ambush and no help of any kind will come from the rogue. This sounds like the Augury will answer if a straight up fight between the enemy and the party, without the rogue's input, will work out for them, probably a "Woe" or a "Woe and Weal", depending on the challenge.