As part of assembling my toolbox of Wizard War tactics and strategies, I am wondering how to passively detect a person covered by Parma Magica.
I am wondering if it was possible to create a trigger that goes off if the weight of a footstep is detected, but zero Penetration InCo/InAn doesn't detect the individual making the step.
eg there is a 50' well with spikes, 6' beneath a certain tile. If a person, that doesn't detect as a person, steps on it, the 6' lid to the well disintegrates and drops the victim mage into the spiked pit.
In practice, I'm not sure how you would do this. Hermetic magic isn't typically mechanical nor are objects typically activated by physics, so an effect to detect pressure is, well, I'm not sure hermetic. I guess you could design something with a mechanical trigger, which is linked to a triple enchantment (one to detect the trap starting to trigger, a second to detect humans/animals, and a third which aims to stop the trap from triggering), but it sounds like a waste of season to be honest because while it would make a distinction between a magi covered by parma and a mundane (by failing to detect the magi), it wouldn't differentiate between a magi and a mundane rock triggering the trap.
Perhaps it is better described as a solid floor with tiles on top.
The trap is under the tiles, and only checks for trigger condition when the pressure of the tile increases by a human weight
I presume there is a limit to the number of traps the defender can afford to create, just as there is a limit to how many precautions the attacker can take during invasion
I may have to think of something different.
I knew there are InTe guidelines to detecting properties such as weight. but indirectly telling weight by the pressure it causes? (or even how much compression a spring might be under)
I'd say that, to avoid parma, your magic must target the tile, not the person stepping on it.
So, if you can detect the position of the tile in space, you can detect if it has been moved.
So, depending on how much it moves, InTe base 2 (learn a visible property) or 4 (learn a mundane property) might be enough.
You'd need a continuous effect, in short asking the question "is the tile moving?", with a linked trigger.
Verrry quickly: stepping on an enchanted item should fulfill the ArM5 p.98 definition of a triggering condition. If the triggered effect is a zero Penetration InCo/InAn R: Touch, it doesn't detect people / animals / beings protected by Parma, Might or specific defenses. Anyway, that InCo/InAn effect might trigger further enchantments via a linked trigger, even if - or specifically if - it doesn't detect something itself.
Silly me.
Especially as I used this before. Rusty rusty rusty!
When you create an enchanted item, you must specify a physical and/or verbal trigger, anything physical, such as "when pointing the wand at someone and saying abracadabra".
As far as I can tell, this is independent of your magical resistance, or else, you'd have to lower your parma every time you want to activate a magical item.
So enchant the tile so that it casts a PeTe effect on itself, with the trigger being "when stepped on it".
Actually, scratch that. "When someone steps on it without saying abracadabra"
There is an InTe spell Level 30 in the base book that allows you to know who touch the ground in a 3Km radius.
You should be able to use a smaller version of that for your detection...
I presume InTe 4 learn a mundane property would not include deformation stress from weight applied. I seem to be fixated on modern physics pressure so much I am losing focus on Mythic Europe "physics".
Or maybe the Herbam equivalent for a parket floor?
I was planning this trap for inside the Defender's sanctum, or other controlled area that the Defender does not expect another mage to enter.
The Defender knows to avoid it, it is to attack any invading mage that gets that far.
Generally, a good way to think about it is: create a non-magical hazard, and then create a 0-penetration T:Circle D:Ring effect that "helps" those affected overcome the hazard (plus possibly, but not necessarily, a T:Circle D:Ring effect to mask it).
For example, if you have 50' well with spikes, just leave it uncovered (or, rather, covered with a rug or a D:Ring illusion). Then cast a T:Circle, D:Ring ReCo spell around it that prevents any human (and possibly animal, with an Animal requisite) from falling inside. Anyone who resists the ReCo effect falls.
A magi would know they resisted a spell effect, however, if the spell boundary is exactly at the edge of the pit, it would need a decent feat of acrobatics and awareness to pivot mid stride.
Since the spell effect is to prevent someone from falling, I would say it would "ping" the parma magica only when the magus started falling... at which point it would be too late, barring some impressive acrobatics (or fast-cast magics).
Though ... that probably deserves another thread, here.