Imaginem + Resistance/Detection

Games Discussion Ars Magica
1

Hey all,

first a quick intro. This is my first board post, I'm new to ArM5 and was a novice at ArM about 10 years ago. However, I've come back to it with gusto! Hope to get to know the community soon. I may attend the Grand Tribunal as my home town is Cheltenham.

To the point. Apologies if this has been dealt with elsewhere. I have spent ages researching however, but came up blank. I cannot see how Imaginem spells which create images of something work. As far as I understand it, there is no resistance check unless the spell casts an illusion on someone [ArM 5e, page 86]. This of course makes sense. I also understand Magi can use Intellego Imaginem to discern an illusion.

My query is with the mundane means of discerning an illusion, whether for a Magus or non-Gifted. At page 115 it talks of fooling beasts and undead, which it contrasts by saying "Demons are very hard to deceive...Certain members of the Church have proven remarkably adept at discerning truth from illusion". This obviously indicates that some form of perception ability can give it away. Indeed in the Guidelines it talks of clues of the illusion.

But I don't seem to be able to find any reference to the game mechanics. One might think the observer should make a Perception+Awareness check to determine if they notice its an illusion. But then what would be the Ease Factor? Surely this would increase with the Maga's success rate?

However, the book appears to suggest the observer makes not check at all. At page 143, mechanics are provided for mimicking a specific object or person. There it is the caster who makes a Perception+Finesse Roll. This provides Ease Factors to "fool" people. 6+ fools acquiantances, 9+ fools friends and 12+ close friends and relatives. This seems problematic to me. First it by specifically providing for a roll when the caster is trying to mimic something, by implication the silence on any other form of roll would suggest its not needed. That would mean a person could never discern an illusion of a more generic nature. Secondly, this roll assumes all individuals of a certain familiarity are equally observant.

Does anyone have (a) a cannon answer or (b) a house rule they have adopted.

Thanks in advance. Sorry to come asking for help on my first post. I shall soon be returning the favour with a very sophisticated excel character sheet which i hope people will enjoy.

Bye for now.

2

First, illusions are dealt with in Houses of Hermes: Societatis in detail.

But a few quick answers:

There are supernatural abilities that help against illusions (especially second sight).
God can do what he wants, so he can decide that His servants can see through illusions.
There are InIm spells that help.
Animals are only fooled if their senses are fooled, so a dog might realize that the "tree" smells human.

3

Hey, thanks for your answer. I'll try and check out Houses of Hermes.

With regards your tips, it's really the last one I'm focusing on. How do you determine if the Animal (or for that matter the mundane human) has their senses fooled?

4

Most illusions don't bother with smell (+1 magnitude). So if the spell was visual + audio only, the smell doesn't change.

You can never be sure though...

5

Basically, the reason illusions don't (normally) deal with Magic Resistance on the part of the viewer is because illusions create "species", kind of like the light that reaches your eyes. If I cast an illusion of a brick wall over an open doorway, for example, the brick wall is illusory but the species that it emits aren't. And since the species aren't magical, there's no need to Penetrate. It seems a little counter-intuitive at first, and totally unlike how illusions are handled in most any other rpg I've ever played, but it seems to work and it makes sense after a couple of shots.

6

Another way to see this is that Imaginem affects the emitter and not the species. That would explain why there are no spells to blind someone by stopping species from reaching him.

7

Please correct me if I am wrong, but it seems to me that the OP is asking how a mundane person can detect illusions, not why they aren't magically resisted.

As far as I know, and I've just skimmed through the relevant Societates pages, there is no way for a mundane to tell. Instead, there is a finesse roll on the part of the caster to determine whether the illusion is 'good enough to fool people', as listed in the original post. As others have already mentioned, illusions can be detected by the observer using a sense that was not included in the spell, eg a visual fire not giving off heat.

Societates p65 and 66 has details of a type of incomplete illusion called 'anamorphs' that rely on the observer fooling themselves which does use a perception+awareness mechanic vs an ease factor based on the caster's finesse plus other things. These are lower level than most normal illusions, since all anamorphs have a base level of 1, but since they also have this 'mundane detection method', they are riskier to use. This implies very strongly that normal illusions cannot be detected by observers and reinforces the lack of such a method in the core rulebook.

(Rolemaster also had undetectable-by-mundane-means illusions; so do other RPGs.)

Churchmen (and others) who have True Faith/a Relic/some sort of Divine Guidance can, depending on the situation/storyguide/die roll, be immune to magic including illusions, but it is not a perception ability as such. See 'The Divine' rulebook for details, plus the relevant bits in the core book.

'Second Sight' also allows illusions to be simply 'seen through', with ease factors listed on p67 of the core book.

Illusions are quite powerful. They are also often quite high level, since each extra sense adds a magnitude. Plus some of the spells in the core book do not follow the guidelines properly and could be higher level than listed. eg the level 20 Phantasmal Animal spell does not include anything to explain why it can create a 'size +1' illusion of an animal, rather than a 'size 0', so it should be Level 25****; nor is there any reason given for it to allow an illusion of any animal rather than one specific illusion. So, if you feel that illusions are too powerful, rule that a spell needs to be specific: each spell only makes one illusion which is the same every time, or insist on extra magnitudes being added for the caster being able to change the illusion on casting. If you make these hard enough, casters will have to use 'anamorphic illusions', allowing perception rolls to detect them....your saga, your choices.
I hope this helps you.

****edit: to correct for my inability to read the book correctly: base individual for imaginem states 'adult human' but does not specify a size. Corpus guidelines also say 'adult human' but includes 'up to size +1' and that shold apply here too, so whilst it doesn't need extra levels for size, you can still claim it should only make an illusion of one animal.

8

Thanks Gilarius. You're correct. I'm trying to figure out how someone (mainly a mundane) would figure out its an illusion.

I understand the point about species, but suppose the Imaginem spell uses all 5 senses. Does this mean, a mundane (or a Magus for that matter) can NEVER detect that it's an illusion? That seems quite remarkable to me. It also belies the comment in the book that an illusion of a bucket does not mean it can hold water, which is a "clue" that its an illusion. Either its a clue (in which case there would need to be a game mechanic for working it out) or its a give away, leading to automatic detection if water is used (which is the opposite of a clue).

Also, that still begs the question, if the illusion is to mimick something known to the mundane, the success is based on the Magus' Perception+Finesse Roll. So a dull-witted, one eyed, partially deaf mundane would have just as much chance of observing the illusion as a Keen-Eye ... you get the picture?

If that is how the rules work, its how it works. But it seems crazy to me.

9

I think the only way for a mundane to detect an illusion is to somehow be forced to interact with it in a way that doesn't work. The illusory wall affecting all senses will not be detected unless someone is forced through it (it wont stop someone, though it will fell like it should). Then it is obvious that it is an illusion (which doesn't mean anyone would see through it, they would just know that it is false).

I cannot remember any ease factor for this. Normally I would let anyone know it's an illusion but would demand some situation based roll (bravery/int/stamina/loyalty) to force themselves against any kind of dangerous looking (like running into a wall) illusion. In a calm situation it would take some time and no rolls.