Another discussion led me to consider the InVi guidelines and I found them to be less than clear. I'll tart at the beginning, so please bear with me.
"A spell to detect items will not also detect effects or creatures, and vice-versa." (DE p.366) So let's split the "detect magic" guidelines into single guidelines for effects (I'm assuming this means active spells and the Parma Magica, with a magnitude equal to the level), items (I'm assuming this means enchanted items, longevity rituals, talisman bonds, familiar bonds, which all have a magitude determined by the pawns of vis), and creatures, using the instructions "Magical items have an effective residue magnitude equal to the number of pawns of vis used to open the enchantment (or the total pawns used for lesser enchanted devices)." and "Magical creatures can also be detected. Treat their Might as the level of the effect; for Hermetic magi, use their highest Art." I hope everyone is with me here.
(I'm really wondering why the guidelines talks about residual magnitude for items and creatures. I understand residues to be what's left after an effect expires. Calling magic items and creatures residues is confusing.=
Level 1:
- Detect active effects of tenth magnitude or higher.
- Detect magical items opened with at least ten pawns of vis (or ten pawns used for lesser items)
- Detect magical creatures with might at least 46 (or magi with highest art at least 46).
Level 2:
- Detect active effects of eighth magnitude or higher.
- Detect magical items opened with at least eight pawns of vis (or eight pawns used for lesser items)
- Detect magical creatures with might at least 36 (or magi with highest art at least 36).
Level 3:
- Detect active effects of sixth magnitude or higher.
- Detect magical items opened with at least six pawns of vis (or six pawns used for lesser items)
- Detect magical creatures with might at least 26 (or magi with highest art at least 26).
Level 4:
- Detect active effects of third magnitude or higher.
- Detect magical items opened with at least three pawns of vis (or three pawns used for lesser items)
- Detect magical creatures with might at least 11 (or magi with highest art at least 11).
Level 5:
- Detect any active effects.
- Detect any magical items.
- Detect any magical creatures or magi.
We are told that the "base level of a spell to detect magic also gives a fairly good idea of the strength of the magic (within a magnitude)."
The guidelines also contain options to increase the InVi spell's magnitude to learn more details.
The guidelines seem to be written for active spells:
- +1 magnitude: "will say whether the effect is Hermetic, and a magus familiar with other types of magic will be able to identify them as well".
- +2 magnitudes: "will give information about Technique and Form, or nearest equivalent for other types of magic" (this will be ReVi for the Parma Magica).
- +3 magnitudes: "gives the rough details of the effect and the sigil of the caster, and reveals whether a Hermetic effect was created by a spell or invested device".
One question is whether this option of adding magnitudes for more detail is also available for items and creatures. Here is an attempt at formulating them.
For items, the transfer for lesser items is straightforward (for invested items see the discussion below):
- +1 magnitude: will say whether the item was created using a Hermetic procedure, and a caster familiar with other types of magic will be able to identify them as well.
- +2 magnitudes: for lesser items, will give information about Technique and Form, or nearest equivalent for other types of magic.
- +3 magnitudes: for lesser items, gives the rough details of the effect and the sigil of the creator
For creatures, this is my attempt:
- +1 magnitude: I can't think of an equivalent for creatures. For Gifted people, it could detect the tradition used to open the Gift.
- +2 magnitudes: identify the Form to which the creature's Might is aligned; for a magus, identify the strongest Art (the Art with the highest score).
- +3 magnitudes: I can't think of an equivalent for creatures. Perhaps this will identify the sigil of a magus?
Discussion:
For invested items, there is a conflict between investigating an item in the lab and via a spell. "Magic items cannot be investigated with simple magic spells. Investigation requires that you spend at least one season in the laboratory to discover what magic an enchanted item contains (see the Laboratory chapter). [...] A spell will suffice to tell you that an item is magical, however, and may give you some idea of its powers. Spells will never tell you how to use an item." (DE p.366)
Additionally, when investigating an item, you "discover the powers in an enchanted device in order from weakest to strongest — that is, from the power of the lowest modified effect level to that of the highest. [...] If you roll and find nothing, it either means that there are no more powers in the enchantment or that you did not roll high enough to find the next one. Only the storyguide knows for certain." (DE p.260) The last point is crucial to me. A spell to detect magic will first detect the effects with the highest magnitude, so it's easy to be sure that you found all the effects. I'm afraid this makes investigating items less interesting, and that this is not what was intended; otherwise the book would say "Only the storyguide knows for certain, unless you cast a simple spell to make sure."
Especially the fact that invested items are detected according to their capacity (the number f pawns used to open the item) and not according to their invested effects tells me that you will not learn anything about the effects. (Always-on effects will register as active effects, of course. I'm talking about effects that are not active at the time of casting.)
My conclusion is that additional magnitudes for more detail are simply not availabe for items. A lot depends here on the interpretation of "give you some idea of its powers";
For creatures, I would not allow the additional magnitudes, because they are not easy to translate. I don't like the idea of finding out easily which is the highest Art of a mage. Can you scan a magus and find their sigil when they have no effects active (I'm not sure whether the Parma Magica displays a sigil)?
What do you think about finding out additional details about items and chreatures?