How do I use Zone of truth to its maximum effectiveness?

[Entessa]

1) I don't understand if the failed save refers to a single instance, or if the save gets applied every time I ask a question.
2) Can a character willingly fail the save? I want to ask an npc to enter and not to resist - is it possible?
3) Is it possible to pair zone of truth with command and tell him to speak exact words? <<I command you to say "I did not kill the king">>

[Grey Watcher]

1) I don't understand if the failed save refers to a single instance, or if the save gets applied every time I ask a question.

I think I've always seen it used as "you save once against the whole spell" not for each individual question. The wording could be parsed the other way, with a save every round, but I don't think that's the intent.


Until the spell ends, a creature that enters the spell's area for the first time on a turn or starts its turn there must make a Charisma saving throw.


2) Can a character willingly fail the save? I want to ask an npc to enter and not to resist - is it possible?

The rules, as best I can find, are silent on whether or not you can deliberately fail a saving throw. I think most DM's rule that you can (with the possible exception of Constitution), but if you're being super strict RAW, I guess not?


3) Is it possible to pair zone of truth with command and tell him to speak exact words? <<I command you to say "I did not kill the king">>

Command must be a single word command, like "confess."


You speak a one-word command to a creature you can see within range.

[Lunali]

1. It's hard to say whether RAW it's roll each round until you fail or roll each round regardless so it's more or less up to the DM how it works.

I typically run it slightly differently, anytime someone lies within the radius they roll a save and on a failed save they tell the truth instead. If the players are the casters I'll roll saves for every statement just so I can tell them if it was a success or failure.

2. I prefer not to allow intentionally failing the save as it removes the possibility of slipping lies through.

3. I find that you rarely need magic to force people to answer, the threat of force combined with a non-answer is usually answer enough. When magic is called for, command wouldn't be my first choice due to the limitations on it.

One thing that should be noted, if the caster is an NPC, there's no reason they couldn't cast it to exclude themselves from the radius and then lie about whether people are resisting the spell.

[Anymage]

The caster explicitly knows whether or not the subject fails on their saving throw. Just continuing to ask them should count for most interrogations unless the target's will save is sky high. (Or unless the target has a Glibness spell, Ring of Mind Shielding, or similar effect. Technically there isn't any contradiction between an effect that renders you immune to attempts to discern if you're lying and a spell that magically forbids you from speaking a deliberate lie, but I'd expect most DMs to go with the spirit of the idea. Especially if you're about to ruin their mystery plot with one second level spell.)

Magically compelling someone to say something vs. magically compelling them to speak the truth tosses the matter into the DM's hands and they won't necessarily rule that Zone of Truth gains primacy. Commanding them to say something, even if it did work, would be counterproductive. Still, being adventurers, nothing stops them from just asking people to assert their innocence and assuming that silence during a turn when the save is failed is an admission of guilt.

Whether or not someone can voluntarily fail a save is left up in the air. However, in this case, I'd allow it. If someone dragged me out of bed at swordpoint and forced me to plead my innocence under magical duress, I wouldn't want the risk of a lucky dice roll to make them just ask me again next round. If I'm honestly innocent, I'd want to be able to make that clear ASAP. If I'm guilty and not an idiot, I'd want to be able to plead my innocence while being under a protective magical effect ASAP too.

[Chronos]

Also remember, of course, that there are a lot of ways to tell the truth misleadingly.

[Keravath]

Interesting. In our local playing with the spell, it has always been a saving throw every round and not once for the spell. I've never run into the other interpretation.

The spell text is:

"ZONE OF TRUTH

You create a magical zone that guards against deception in a 15-foot-radius sphere centered on a point of your choice within range. Until the spell ends, a creature that enters the spell's area for the first time on a turn or starts its turn there must make a Charisma saving throw. On a failed save, a creature can't speak a deliberate lie while in the radius. You know whether each creature succeeds or fails on its saving throw. An affected creature is aware of the spell and can thus avoid answering questions to which it would normally respond with a lie. Such a creature can be evasive in its answers as long as it remains within the boundaries of the truth."

A creature that enters OR starts its turn there must make a Charisma saving throw. I don't really see how that can be read other than every turn the creature starts its turn there it has to roll.

The spell Spirit Guardians uses exactly the same wording:

"An affected creature's speed is halved in the area, and when the creature enters the area for the first time on a turn or starts its turn there, it must make a Wisdom saving throw."

Do folks who treat Zone of Truth as one save also assume that a creature in Spirit Guardians has failed so they take the higher damage every round?

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Anyway to the OP:
1) I think that a save is required every round (the wording is similar to other spells that are usually interpreted as a save every round). You know whether the creature has passed or failed that round and thus whether they must tell the truth that round or not. You can probably ask one question/round.

2) There are no options to willingly fail the save as far as I know. Some spells and effects include that wording but it appears to be on a case by case basis. However, with a save required every round, with a 10 minute duration, the creature will usually fail on some of those rounds so you should be able to get a truthful answer. If a creature wants to tell the truth then it can just answer on rounds that you know they are telling the truth.

3) You could combine Command and Zone of Truth. However, command is only one word so you would need to get creative with what word you use in order to get the answer to the question you are looking for. Note that having someone else cast Detect Thoughts at the same time as you are employing Zone of Truth can offer additional insight since if the creature is thinking about their words carefully enough to try to lie while the zone is active, the person with detect thoughts should pick up on that.

"You initially learn the surface thoughts of the creature-what is most on its mind in that moment."

If the creature is thinking hard about lying then that will likely be what is most on its mind.

"Questions verbally directed at the target creature naturally shape the course of its thoughts, so this spell is particularly effective as part of an interrogation."

Suggestion might also work to get information but the creature affected would probably need to believe that there was no harm associated with a truthful answer.

[MoiMagnus]

You can probably ask one question/round.

I'd say it's not that easy. You can ask a lot of questions in 6s. But on the other hand, a single answer can span over multiple rounds if the targets is stalling for time.


1) I don't understand if the failed save refers to a single instance, or if the save gets applied every time I ask a question.
2) Can a character willingly fail the save? I want to ask an npc to enter and not to resist - is it possible?
3) Is it possible to pair zone of truth with command and tell him to speak exact words? <<I command you to say "I did not kill the king">>

First an foremost, Zone of Truth is one of those "heavily influence worldbuilding" spells. Its existence at a reasonably low level means that plenty of NPCs around the world use it, and that societies have been influenced by its existence. As such, a lot of GMs houserule it in a way so that it doesn't break the societies they build (sometimes not even realising that they're using a houserule).

As for actual answers:
(1) Save every round, which is really unpractical so could be worth a houserule.
(2) Impossible by default. I'd argue that if you train yourself, you can probably force yourself to fail, but it's like forcing you to not closing your eyes as a reflex, it's not that easy.
(3) Command is a single world. You could ask a yes/no answer and use command to say "ANSWER!", but you might want to talk with your GM beforehand to know how it would behave. You can even explain to your GMs that you try this on a teammate during downtime as a little game to test the limits of ZoT and Command.

[Corran]

First an foremost, Zone of Truth is one of those "heavily influence worldbuilding" spells. It's existence as a reasonably low level means that plenty of NPCs around the world use it, and that societies have been influenced by its existence. As such, a lot of GMs houserule it in a way so that it doesn't break the societies they build (sometimes not even realising that they're using a houserule).
It's a fun spell to think about in that regard (how it might influence a society). What if the one who casts zone of truth is in whatever plot they are supposedly try to help uncover. What if they are corrupt and they were simply bribed? Do you have another person cast zone of truth to the one casting it? And then another, and then another? It's logically to assume that such things will have happened when no one was the wiser, and that as time passed the society became aware of such dangers. So how does a society handle this. Are there specific individuals appointed for such a task that only their cast of zone of truth carries weight with whatever local authority (so judges essentially), and if so who is the one tasked with appointing them? How many of them use this position to their advantage instead of just serving it honorably? If the risk of corruption is real and something that the society acknoweldges, are there laws in place that make it more difficult to approve/acknowledge a zone of truth against members of certain groups (nobles, clergy, influential merchants, etc) and how much breach of the eticquette would it be to ask such an individual to undergo the proccess? Or what would it take to make forcing it on them legal?

[Kane0]

I like to combine Zone of Truth with Detect Thoughts and a friend with Insight expertise and/or advantage for best chances.

[Gurgeh]

tbf I can understand people assuming the save is a single all-or-nothing affair because that's exactly how it worked in 3.5.

The unfortunate problem with the spell is the caster knowing a save's outcome and the target knowing the spells' effect combine to make it less of "zone of truth" and more a "zone of no lies" (yes, the distinction is meaningful). If someone fails their save then you know they're not lying; if someone passes their save then you know they able to lie but have no idea whether or not they will - so you can have the perverse outcome of a genuinely honest character's testimony being doubted simply because they had the misfortune of passing a saving throw, in ways that it wouldn't have been if the spell weren't in play.

It's compounded by the one-save-at-a-time mechanic because any successful save is going to immediately inform the caster that they can't trust anything that round - so it will lead to the caster stalling for time or just going with a nothing-question to mulligan the save and fish for a failure in the future, since the target's virtually guaranteed to fail at some point in the spell's 60-round duration unless they have truly stratospheric bonuses or can benefit from time pressure (one in a big line of people being asked the same question, stalling for a distraction that lets them escape, etc.) There's definitely potential for some drama in this sort of situation, but more often than not it's going to lead to a inversion of the Three Stooges Try Stealth Checks problem, where a save failure (and therefore party success) is effectively guaranteed and everything that happens on the way is so much incidental noise.

[Kurt Kurageous]

I am unclear about what rounds have to do with anything unless you cast this in combat. If you reclassify this as 'social combat,' I'm going to say you are going to run into problems, as 5e is just not great at simulating everything that can happen. That's why we have DMs.

[Chronos]

Corran, the simplest answer to your question is if the relevant authority is themself able to cast the spell. Granted, not all leaders are spellcasters, but a lot of them are.


Quoth Keravath:

Note that having someone else cast Detect Thoughts at the same time as you are employing Zone of Truth can offer additional insight since if the creature is thinking about their words carefully enough to try to lie while the zone is active, the person with detect thoughts should pick up on that.
Depends on the person. For fey, for instance, telling the strict truth, but in the most misleading way possible, is second nature. I've even seen it happen when it served the interests of the fey in question to not mislead... but they were misleading anyway, because that's what fey do.

And there are some non-answers that are easy enough that they don't require any more thought than normal speech. Answering every question with another question, for instance, is a good one.