OK - so, one of the players in our game has decided to make a new character - their old one didn't, in his opinion, have enough story hooks. So, the new one is an spont-focused magi (house Diende, but the PC's obviously don't know that). My character plans on making every magi in the covenant a lesser enchanted item that makes spont magic easier. In particular, the ReVi effects of "create a mystical connection to the target, thus allowing you to cast at Touch range" and the "Extend the concentration" effects. So by using the item (basically a magic wand or staff), the user can add up to Sight range and Moon duration, while only having to have to cast the improv spell at Touch/Concentration, respectively.
My question - can these two effects be considered "the same" effect, in terms of creating a lesser enchanted item (ie, one is the base effect, and the other is defined as a +1 magnitude of complexity)? They both fit under the general heading of "improve the quality of the cast spell", they both come from the same Form/Technique bonus, but they are obviously different effects. However, enchanted items aren't quite as fixed in the limitations of hermetic magic as spells are - from what I understand, the spell list is a place to start, rather than the definitive example of what items can do.
I don't think I agree with this part. They're just as limited, except where rules say they're not (or when they say that the item is MORE limited).
"Improve the quality of a cast spell" isn't one of the spell guidelines for ReVi effects. It sounds much more like MuVi (since there are examples such as Wizard's Reach).
Here are my thoughts on the effect you've described:
If you're after a raw MuVi effect, this is essentially equivalent to adding +2 magnitudes to a spell, one for range and one for duration. This makes it fall under the "Totally change a spell" MuVi guideline, while not requiring a Creo requisite. I'd make it two magnitudes higher than a Wizard's Reach of the same level - the spell is adding an additional magnitude to the effect beyond what Wizard's Reach does, and the other magnitude is for complexity. So, while my knee-jerk reaction is to say this should be two effects, it seems OK for a single effect at a higher magnitude.
MuVi spells/effects don't work on spontaneous magic (ArM5 p. 159). Now, this might be allowable as part of a House Diedne mystery, but that makes it REAL easy for a player to expose their Dark Secret and end up being marched.
MuVi effects in items can only modify effects instilled in the same item (again, ArM5 p. 159). So, putting this into a lesser enchanted device is a waste of time - it can only modify another effect from the item, which the item can't have. So, it'd have to be a spell instead of an item. I can't see a House Diedne mystery getting around this one.
If you're after something more like Opening the Intangible Tunnel (which is ReVi) to increase range (instead of Wizard's Reach to increase range), you could make a Sight range version of it (1 magnitude lower than Arc), and have the item maintain concentration. This would work for spontaneous magic just as well as formulaic (without any risk of discovery!), but can't increase the duration of effects cast through it (even as a multiple-effect spell instead of an item, it could only affect a single other spell as it is cast). You still wouldn't be able to put a MuVi effect in an item to increase the duration of spells cast through it, though - nor would I let a spell do both. You'll also have to put penetration into the device if you want to use it through Magic Resistance, and opens you up to magical counterattack for those who can perceive the tunnel. Still, such an item definitely has its uses.
That last paragraph started me thinking, and the following paragraph is purely stream-of-thought: A Mu(Re)Vi effect, combining Opening the Intangible Tunnel (Mom duration, and either Arc or Sight range) with a Wizard's (Endurance? Can't remember the book or name which described increasing duration to find what it was named) effect to add +1 to the duration of one spell cast through the tunnel. The MuVi guideline is more stringent (level up to +1 magnitude vs. level up to +5 magnitude) ... but then how to determine the proper Range to the Target? This is where I notice combining the effect wouldn't be possible because the Targets are different - the ReVi effect targets where the Intangible Tunnel connects to, while the MuVi effect targets the spell being cast.
tl;dr: At the end of the day, I'd recommend making an Arc/Mom/Ind spell or item for the Intangible Tunnel effect, either mastered for fast casting or using item option for fast-cast speed from HoH;S (serf's Parma, can't find the book right now), and then have a separate Wizard's (Endurance?) spell to cast on what will be sent through the Intangible Tunnel
Intangible Tunnelss. You might want to have a look at Hermetic Projects, chapter 5, in particular p. 78ff.
No. If you want to do them as variations on the intangible Tunnel, you're essentiallt Re-creating The Evil Eye and The Master's Message (HP, p. 80-81 and 81 respectively).
Also please note that magi wishing to use this tunnel must be able to sense it.
This is not automatic, as the caster in this case would be the device - not the magus.
They come from different guideline, so no.
This is really your answer.
Items are generally less flexible than spell, which is also why devices generally cannot use MuVi effects (except to modify their own effects).
Absolutely, nor is it a definitive list of what spells you can invent.
However, it gives a lot of information about what can be defined as a single 'effect' - for either a spell or a device.