Perdo Mentem "Invisibility"

Games Discussion Ars Magica
1

Last night something came up in my ArM game, and I'm not sure how to make the judgment call.

A mage wants to enchant the door to his sanctum with a PeMe with a larger than Momentary duration. His hope is that he can instill an effect which, when the door is touched, not only causes someone to forget that there is a door, but prevents them from relearning the existence of the door until some time later. So, even though the door is still right in front of the target, he can no longer comprehend its existence.

I'm not sure
A) whether that's really possible with Perdo Mentem, or whether there should be more restrictions on the power, and

B) what the magnitude should be of the effect at Range: Touch, Duration: Sun, and Target: Individual.

Any guidance?

2

Check out the Perception magics and principles of Mentem magic as detailed in the Jerbiton chapter of HoH:MC. That might give you sufficient fodder for making an informed ruling for your saga.

3

I think that it's definately possible. Triggered by someone touching the door, unlimited uses per day, the parameters that you describe..

I don't even think that it's a border case. It looks uncomplicated in design.

What's making you hesitant?

4

What's making me hesitant is that I feel that, even more than Tip of the Tongue, the door is still there, and so there should probably be a chance for the target to move beyond the magical clouding to some extent.

I'm thinking of a situation where there are three grogs trying to sneak into the sanctum, one touches the door, and immediately finds himself unable to open it, there's no door there. The desired effect is that grog can't open it even with the other two yelling, "open the door! It's right in front of you!"

I have this niggling feeling that it just should be limited or higher magnitude for effect, but if not, I'll apply it straight.

5

It has a definitive faery tale/magic tale feeling to it, so I would say it is possible. Basically you REFUSE to aknowledge the item's/person's existance no matter what the others yell at you. PeMe no problem. The grog would rationalize that what he is touchuing and appears to be a door handle is in fact a weird irregularity in the stone wall and some stuff like that. he will RERFUSE to believe there is a door there until the spell expires. Once the spell expires he is likely to say that he knew the door was there all the time, but refused to enter the room on his own free will, of course.

3 days ago I saw a movie based on an original story of Neil Gaiman (my favourite fantasy author). There is exactly the situation you are mentioned there (well, almost). It is a 100% classic faerie tale, but the situation can be replicated with hermetic magic without much problems..

SPOILER ALERT!!!!!!!!!!

Not a big spoiler, but a spoiler none the less :slight_smile:

A witch is enchanted so that she cannot see a character (a fallen star) by the queen of the witches. She cannot see, hear or perceive the star-girl in any way (and she cannot touch or be touched by her as well (but that is ReCo, so we will leave it out of the equation) and refuses to aknowledge that the falling things around her et al are caused by the star-character moving stuff around.

Cheers,

Xavi

6

Ah, yes, Stardust. I have the DVD. Didn't think about it that way.

7

Certainly possible, just one thing though, i would say its MuMe rather than Perdo, and ReMe might also be argued.
Guidelines can be said to be a bit fuzzy sometimes and this is certainly one of those "sometimes".

You change how the "touchee" perceives whats in front of him, its not just a removal of a perception, its a clearly altered perception as described.

If you dont want to allow it as too easy you could even argue that the door effect actually is both a PeMe and a separate MuMe or ReMe effect.

Ie:
PeMe
when the door is touched, not only causes someone to forget that there is a door
MuMe/ReMe:
So, even though the door is still right in front of the target, he can no longer comprehend its existence.

Both effects potentially have laughably low base levels.
At most level 10 for the PeMe effect(remove "minor memory", although if its extremely important for a person to get past the door, maybe it should qualify as a "major memory" and get level 15, at the same time, if you call it an "important detail" instead, its just level 4), MuMe would be anything from level 2 to level 5, ReMe would be level 5-15 and very hard to judge exactly, you might even argue that its a CrMe effect of "creating a memory" ie level 5 telling the affected that he really didnt see a door and there never was one there, and he just hallucinated or something.

You could even pick the whole effect apart and require a spell each, CrMe, MuMe, PeMe and ReMe for it to work properly.

And the alternative would of course be to go the opposite way and make it a unified PeMe with Cr,Mu,Re requisites(id prefer it as a MuMe base spell, but the base level there is so low that it would just be too easy i think).

8

Well this "being unable to see the door from a given angle" is precisely what the Jerbiton perception section goes into in much detail. You could enchant a cone effect which would impact only the character(s) standing in the field of the cone whilst those outside it would be unaffected. Granted this falls under the heading of "Transparency (illusions)" but should provide solid principles for application in other types of illusions.

Just make the trigger "touching any part of the door".

As far as using PeMe (or MuMe) for that matter, check out page 66 of HoH:Societates for ideas using Mentem (Created Emotional Bias, Diminished Mental Capacity). Realize, however, that use of Mu/ReMe often allows for natural resistance rolls. Perdo would be much more effective and perchance long-lasting since that comprehension factor would have been fully destroyed and would have to be relearned.