One problem that I have with the various ways of determining falsehood in 3.5/PF is that none of them are foolproof. There are a few spells that help with this, but they all allow saves. Zone of Truth is especially bad, since you don't even know if a particular character failed the save or not, and the affected character is aware of the effect and can clam up if they want.

Is there a way to force a character to tell the truth (or at least know if they're lying) that doesn't allow a save, or SR, or any other form of resistance? I'd be happy with answers that just get by save and SR, as I feel that it's unlikely that anything is going to get by Mind Blank or other such total protections. I'm happy with answers that address either 3.5 or Pathfinder, but please note which you're answering.

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    \$\begingroup\$ This would be terribly boring in play. \$\endgroup\$
    – okeefe
    Jun 20, 2013 at 5:39
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    \$\begingroup\$ @okeefe: Depends how sneaky your GM is. There's no easier way to fool people than with the truth. \$\endgroup\$
    – Tynam
    Jun 20, 2013 at 6:24
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    \$\begingroup\$ Even if you can force someone to tell the truth, you still need to worry whether they're telling the whole truth. When a tanar'ri tells you "There are no enemies waiting in the cave," you'd better be prepared for enemies doing something other than waiting, people who won't be your enemies until you enter, enemies in an artificial room that's technically not part of the cave, unintelligent monsters who don't understand the concept of enmity, extremely powerful monsters who don't think of you as anything more than a distraction, and the entire cave turning out to be an illusion. \$\endgroup\$
    – GMJoe
    Jun 20, 2013 at 7:10
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    \$\begingroup\$ @GMJoe - and even better; people who are his allies, and thus, not enemies (to him). Whether they will by default have enmity towards the PCs is a separate matter. \$\endgroup\$ Jun 20, 2013 at 18:38
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    \$\begingroup\$ @DuckTapeal Anywhere the characters go is part of the adventure. Going the wrong place first sounds like a fun and memorable adventure! \$\endgroup\$
    – okeefe
    Jun 21, 2013 at 1:38

5 Answers 5



You could cast Geas/Quest on the target, this is however a 6th level spell but it only allows a chance of SR - no saving throw. So it's nearly what you want, but it's not going to get around mind blank sadly as it's mind effecting.

The spell text states:

While a geas cannot compel a creature to kill itself or perform acts that would result in certain death, it can cause almost any other course of activity.

So you could easily compel/quest a target to "only speak the truth for 24 hours"

Lesser Geas/Quest allows a Will saving throw.

Spell available in both systems.


Failing that you could cast Commune after the subject has said something and ask the patron "Did X speak the truth?". This divination spell isn't directly targeting the subject so may get around this (GM advisement I'd feel)

Spell available in both systems.

Mark Of Justice

Your best chance, probably, I think is Mark of Justice which is neither mind effecting or a divination spell so mind blank isn't going to help. It only allows spell resistance, no saving throw. However the spell does need 10 minutes to cast on the subject however. What it allows is:

Typically, you designate some sort of undesirable behavior that activates the mark, but you can pick any act you please.

So you could designate the action as "lying" and have the curse as, well, it depends how nasty you're feeling. Or if it's a simple interrogation the curse could be that the victim turns orange for 10 minutes - curse over and lie detected.

Spell available in both systems.

  • \$\begingroup\$ Geas and Mark of Justice are fun in combination. Mark: "Don't lie", Geas: "Tell us all about your rebel friends, truthfully." \$\endgroup\$
    – C. Ross
    Jun 20, 2013 at 12:12
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    \$\begingroup\$ Unfortunately, just breaking the terms of geas and mark of justice isn't that painful. The only advantage to them for this is you might make mark of justice's effect really obvious so you know if they lied. Commune (and similar divinations) are a good idea, though. \$\endgroup\$
    – KRyan
    Jun 20, 2013 at 13:33
  • \$\begingroup\$ I'm accepting this answer because I feel like it provides the most reasonable ways of achieving this effect. Geas is mostly foolproof (at least in Pathfinder, where they can't just refuse the geas), Commune is very good at this kind of thing, and Mark of Justice gets by Mind Blank quite effectively. \$\endgroup\$
    – DuckTapeAl
    Jun 21, 2013 at 1:37

Sense Motive, DC 100.

The Epic Level Handbook (page 44) describes the ability of the Sense Motive skill to detect surface thoughts. The target DC is 100, and the effect is non-supernatural, non-spell, non-spell-like: entirely and utterly mundane. There is no saving throw, no spell resistance, no attack to miss.

If the target can achieve a Bluff of 100 and is actively using the skill application (on page 39 of the same book) which lets him disguise his surface thoughts, then this becomes an opposed check in which rolls below 100 fail automatically.

Naturally, this option probably won't be viable for most characters for obvious reasons, but it's worth mentioning because it is totally mundane: this means it bypasses nearly every attempt to avoid thought detection--including mind blank and the Spymaster's "Deep Cover"--because most defenses specify magical and/or device-based snooping. It requires a visible target within 30 feet, though.

Pedantry note: The ELH is technically 3.0, not 3.5. However, it was given an official 3.5 errata update which didn't change these abilities at all, and they are currently found in the d20srd.

  • \$\begingroup\$ Would sense motive's detect surface thoughts break through a spymaster's deep cover? I guess it can't (dndtools.eu/classes/spymaster) \$\endgroup\$ Jun 20, 2013 at 8:05
  • \$\begingroup\$ @Alticamelus "While she operates under deep cover, divination spells detect only information appropriate to her cover identity; they reveal nothing relating to her spymaster persona." As Sense Motive is a skill, not a divination spell, I see no reason why Deep Cover would prevent the use of this skill application. \$\endgroup\$
    – BESW
    Jun 20, 2013 at 8:07
  • \$\begingroup\$ I think it may be worth mentioning to give an impression of how hard would be to determine without any doubt if someone is telling the truth. \$\endgroup\$
    – Flamma
    Jun 20, 2013 at 10:08
  • \$\begingroup\$ "a spymaster becomes able to quiet her mind and completely immerse herself in her cover identity" - under Deep Cover, the spymaster's surface thoughts would not give any indication that she is lying. \$\endgroup\$
    – Brilliand
    Feb 13, 2014 at 0:25

The closest thing I have ever come across, in Pathfinder, to what you're looking for would be one of Abadar's spells, Fairness. It offers both SR, and a save. However, SR can be lowered, and will saves can be willingly failed. So, you can tell something to submit to it, and will know upon casting whether or not they have done so, as it will be obvious when the key doesn't appear above their head that they offered some resistance that you couldn't overcome.

Other than that, dominate spells are about the closest thing you'll get to absolute certainty that someone is telling the truth. You'll know if the spell is in effect because it will tell you, and they literally cannot do anything but tell the truth if that's what you tell them to do. Unless, of course, you're dealing with the master-spy prestige class... in which case, you're being set up to fail with that particular strategy, so I would suggest finding an alternate route to achieve your goal.

  • \$\begingroup\$ -1: I can't see how Fairness would prevent lying. It could prevent someone from lying about a trade agreement, I guess, but that's only applicable to really specific situations. Then again, I'd give a +1 for the suggestion about Dominate, so that evens it out. \$\endgroup\$
    – DuckTapeAl
    Jun 20, 2013 at 16:13

One feat everyone missed: Master Manipulator, from PHB2. If you Sense Motive over their Bluff, you then make a Diplomacy check against their Bluff. If you win, they reveal their lie.


There's some little tricks to get someone to tell the truth. First, you need to be sure they don't have any magic protecting them. Since divination spells are filed by nondetection and similar spells, cast on them some spell that has no save and is dismissible. If you can't register the aura, the target is protected against divination. Tell him to dismiss his spell and check again. The only way to counter this is to cast the spell without anyone noticing after the test. Then you need to cast over them a spell that forces them to tell the truth. Ask him to willingly fail the save and check for magic again. Then, be sure to ask really careful questions.

Intimidate checks might be another way to force out the truth if the GM goes by RAW. (Intimidation in real life is a good way to get hasty lies.)

Or you can try the DC 100 check suggested by BESW in his answer.


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