Thaumaturgy question (another newbie!)

[Monkey Bloke]

Hi all,
I was planning to begin running a DFRPG campaign in a few months when our WFRP game has wrapped up.
With our current GM away for a couple weeks, we took the opportunity to run a quick DF scenario, mostly to familiarise ourselves with rules etc.
Most of the time of these two sessions degenerated into flipping through the magic section.
We even got the the point where we were considering no magic users or only being able to use spells we have pre-"sorted out" due to the time it took to figure out spells.
Since neither of those ideas is appealing, I figure the best idea is to use the next few months to get a proper handle on spellcasting in DFRPG.
I figure my easiest option is to ask a buch of questions here.

So, one of ideas that we had trouble with was the following:
The players have a local criminal who they suspect works for a black court vampire. They want to question him and to develop a lie detection method, a kind of "magical polygraph" I guess.
Trying to avoid the laws of magic, the goal isn't to control his mind, simply to detect lies (the polygraph analogy is reasonably accurate).
They drew some of his blood for the spell and then we hit a hurdle on how to model this spell.

We considered a few ways to do this, but couldn't figure out the best way to model it. One this that did come up was temporarily increasing the PCs Empathy to detect lying, but other than creating a huge load of taggable aspects via a magical manuver we couldn't suss out how to increase a skill, even temporarily.

How would people here want to model a magical polygraph on an unwilling (but secured) target, and what sort of numbers would be involved?

Thanks.

[cgodfrey7]

I am a newbie also, but hope I can provide at least a direction to answering your question.  Some physical responses associated with telling a lie are increased heart rate, dilation of pupils, increased respiration, change in posture, and change in vocal patterns.  If someone were able to detect these minute changes in the person being questioned, that would not be an invasion into their mind using magic.  I would think that Supernatural Sense (YS 165) would cover these possibilities.  To give this temporary ability to someone, I looked at YS 265 Meneuvers and Contests and Conflicts.  Assume the person receiving the Supernatural Sense is going to allow it to happen (Resistance +0).  Maybe 2 shifts to give a -1 Refresh power.  5 Shifts to go from instant length of time to 15 minutes.  I come up with 7 shifts.  Minor comment though, during those 15 minutes the person receiving the Supernatural Sense aspect will be inundated with sensory overload as he/she is not used to the extra input, so normal talking may sound very loud, normal lighting may be extremely bright, etc. unless they have had this done to them several times before in which case they would be used to it.  Hope this helps, and I hope I am target with my numbers.

[Belial666]

If you want to do something mind-related and NOT have it be mind affecting, you should use Biomancy.


Have the spell be a biomancy-based divination in detecting body language and physical tells of lying. The shifts you put in the spell would be the skill roll you'd have for detecting a lie. I.e. if you put 10 shifts, then the other guy would be caught in a lie if he rolled Deceit lower than 10.

[MyNinjaH8sU]

How would people here want to model a magical polygraph on an unwilling (but secured) target, and what sort of numbers would be involved?

I believe Empathy is used to detect Deceit. Using the rules on YS263 under the heading - Solve Improbable or Impossible Problems - you would determine the difficulty the same as you would a skill roll. This is only if it is a simple action, equivalent to a skill roll in complexity.

Personally, I would treat it as an ongoing ritual, with both the Wizard and the target inside the circle, and have the spell be either Biomantic (as was pointed out) or Telepathic in Origin. The Biomancy version would be a sort of hyperawareness that would be able to sense minuscule changes in hear rate, blood pressure, pupil dilation, perspiration, and more; allowing you to paint a picture of when the subject is being honest. This I would treat, mechanically, as an extended contest or conflict between the Wizard and subject - really, it could be a full on social conflict, with magic used in place of social skills like Empathy.

Alternatively, if the Wizard just read the subject's mind as he asked questions, he could verify the truth easily. I would treat such a spell as a sort of mental block against lying. The subject can't hide his thoughts without rolling higher than the block on Deceit or Discipline to drive the Wizard out of his mind. This certainly is Grey magic at best, and, were I running the Conflict, would warrant a Compel on the High Concept of the Wizard, to resist looking a little deeper, and maybe pushing to make the subject a little more compliant... slippery slope kind of stuff.

Does that help?

[Haru]

I think what you are trying to do is a social conflict (the interrogation), and for that you are trying to get some advantages. Instead of trying to figure out how to cast the spell, lets have a look at what you want to do.

A polygraph helps you to sort out lies, not a 100 percent, but it can be pretty useful. In a manor of speaking, it protects you from being lied to, or in other words: it protects you from a deceit attack. So a regular polygraph would be an armor:1 or armor:2 against deceit attacks in a social conflict (mostly interrogation, obviously).

Creating a spell from that is pretty easy. You want to create a block that is used as an armor, so for every point of armor you need 2 points of complexity in your spell. So you would be at 4 shifts complexity for the armor:2, maybe add 1 shift to make it last the scene (not sure if that is necessary).

During the interrogation, anytime your suspect tries to lie to you using deceit, you can defend yourself using empathy + armor:2, effectively raising your empathy 2 points for the duration of the scene.

The last part now would be to add color. Maybe the wizard hears the voice change, or the words flow out of the suspects mouth and change color, there are a lot of ways to describe this.

Keep in mind though, that there are people that are trained to lie to a polygraph, and maybe those techniques can help against a magical polygraph, too. In that case I would turn the tables around, instead of the polygraph being an armor for you it would become a weapon for your suspect.

[Blackblade]

You could also try the old "bowl and photocopier" method; have a wizard make a few magical maneuvers that give the appearance of being a "magical lie detector," then have another character tag the temporary aspects and use deceit to convince the prisoner that they are reading his mind.

[sinker]

A polygraph helps you to sort out lies, not a 100 percent, but it can be pretty useful. In a manor of speaking, it protects you from being lied to, or in other words: it protects you from a deceit attack. So a regular polygraph would be an armor:1 or armor:2 against deceit attacks in a social conflict (mostly interrogation, obviously).

Of note Deceit is often used as a defense against empathy assessments. The armor wouldn't help with that.

[Haru]

Of note Deceit is often used as a defense against empathy assessments. The armor wouldn't help with that.

You're right, but I think in this case it should be this way around. If it does not fit, you could just make it a weapon:2 spell for empathy with 3 shifts total, or combine the two spells to a 7 shift spell and you get both. In this case however, I think the armor version should be the way to go.

[danthehut]

Could you use The Sight to do some kind of lie detection?

YW223 states "Other times, it’s the shortest path between mystery and truth".

[Haru]

I'm pretty sure you can, but I wouldn't recommend it. The chapter about the Sight also says, that it is kind of a "last resort", if you have absolutely nothing else you can do. Remember, that you get stress every exchange you keep your Sight open. If you have time to prepare a spell that lets you do things without using the sight, take it

[sinker]

Actually that seems like one of the tamer ways I've heard the sight used, and it might actually work. Keep in mind two things though. One it could all come out as confusing gibberish that you don't understand and two there could be a raving monster inside that fairly innocent looking prisoner.

[devonapple]

Considering that even a Soulgaze isn't an accurate lie detector (so much as a gauge of one's character), I don't see how The Sight would discern truth from lie other than by stripping away illusions and exposing magical energies. If a creature were using magic to fool others, that might be revealed by The Sight. It's an effective shortcut for many questions, but other than showing the true nature of the subject, I don't believe it would be fine enough to discern actual lies. A demon should appear the same to The Sight whether it was lying or reciting a grocery list, even an evil grocery list.

[Monkey Bloke]

I think what you are trying to do is a social conflict (the interrogation), and for that you are trying to get some advantages. Instead of trying to figure out how to cast the spell, lets have a look at what you want to do.

A polygraph helps you to sort out lies, not a 100 percent, but it can be pretty useful. In a manor of speaking, it protects you from being lied to, or in other words: it protects you from a deceit attack. So a regular polygraph would be an armor:1 or armor:2 against deceit attacks in a social conflict (mostly interrogation, obviously).
<SNIP>

I think that Haru answered my question and made me realise something about the best way to use magic in DFRPG, I was caught up with trying to model a specific effect, when modelling the overall desired result and filling in the details with wahtever colour is needed is a better way to go about it.

Thanks.