Manipulating non-concentration spells after casting them

Games Discussion Ars Magica
1

Hi!

We have a discussion in our group regarding whether you can change how a spell behaves after casting it if it has a duration other than concentration like diameter, sun, moon or year. My interpretation is that spells works after the fire-and-forget principle unless they have a duration of concentration or that you somehow can interact with the target of the spell (i.e. communicating with someone who obeys you according to a Mentem spell.) This means that a ReCo fly spell with sun duration only moves you in a fixed direction and speed for the duration of the spell. If you want controlled flight, you need a concentration duration ReCo spell (you could of course use Maintaining the Demanding Spell to avoid the need to concentrate for a period.)

How do other groups interpret this? The rules are, as usual, not adressing this particular issue AFAIK.

2

For the most part, I agree with you that once a spell is cast, the caster loses control over it, but there are at least two canonical exceptions. First, casters with Harnessed Magic may retain control and secondly Muto/Corpus spells such as "Shape of the Woodland Prowler" or "Cloak of Black Feathers" which enjoying despite Sun duration may be terminated earlier than that by removing an associated prop - this is because the creator of said spells possessed Harnessed Magic...

3

We just assume that stuff works like Phantasmal Animal (from the corebook) does: one can manipulate non-concentration spells after casting (if they are designed that way) by mental effort alone, provided that the caster is within range of the target and can concentrate on the manipulation - when concentration lapses or the target moves out of range the target is affected in some default way (frezees, or keeps going in the same direction/performing the same task etc.)

4

agreed.

Which means this special case is based on a Virtue

This is a feature of MuCo spells (it's in the MuCo-guidelines' box), so no reference to Harnessed Magic (even by proxy) is needed - that feature is retained even if you re-invent the spell (or other body-shifting spells) from first principles.

EDIT: Editted because I forgot a point.

5

I was wondering about this too. Considering the implications too.

In the projects book (living corpse) there are corpse animation spells with sun duration which recognise voice commands... What's that about? Effect of rego? A cool necromancy special? Something to do with corpses being able to understand voices before they were corpses?

Can you do that with other forms?

Sorry, not really answering the op, but does add to the debate! Any insight would be really appreciated.

6

I think whether a spell can be controlled after casting depends solely on how it was designed.

From p111 of the main rulebook

That is certainly the guideline that is used in Phantasmal Animal and Phantasm of the Human Form, spells of duration other than Concentration but that can be controlled. It also appears there is additional levels of magnitude (+2) in order to do this.

7

The reference to the core book in the previous post goes with my understanding of the rules - you don't need Concentration duration on Rego Corpus spell to achieve controlled flight. (Keep in mind though that suppressing an effect is something else than controlling an effect, so there are still a lot of spells where Concentration duration is more useful than longer durations - illusions being a primary example.)

8

Also note that a non-fatiguing spont for a PeVi "cancel my own effect" is probably one of the easiest spells to cast in the game: it has +5 magnitudes [I think], and you can probably do it at Touch range, and you add in an extra quality die roll to the level at the end. So it's pretty easy to cancel out your own lvl 15 or 20 effect. And hey - with that quality die roll added in there, if you fail you can just cast it again...

Cleansing Touch (PeVi lvl 2 (Base Effect, Touch +1) Cancels out any specific spell a magus can recognize, up to lvl 10 + a quality die roll.

Anyway - that's the reason I don't have a problem with duration outside of concentration - it's usually pretty easy to just shut down your own magic, anyway.

9

If Muto Vim spells must be voice to affect one's own spells, then I would think that so to would Perdo Vim effects behave the same.

10

Touch range is sufficient to affect your own spells with Muto Vim. It says so in the guideline

11

Perdo Vim follows different rules though - Muto Vim is special as in that it affects a spell as it is being cast. Dispelling something is simply the range to the target of the effect you want to dispel - in case of an effect on yourself "Personal" should suffice. Also it is irrelevant who cast the spell, as the rules for dispelling effects don't discriminate in that regard, the difficulty is based solely on the level of the effect. Dispelling is also form-specific in that you need to invent seperate spells for different hermetic forms, unless you take a general "dispel any magic effect" approach, which halves the effectiveness of the spell.

(P.S.: The guideline is +4 magnitudes, not +5.)
(P.P.S.: Also, it's not a "quality die" as in ArM4, but a "stress die (no botch)", which is different as in that 0 still count 0 and not 10. :wink:)

12

Re: the guideline - Ah, cool. Thanks. I'm doing this from memory at work. Not Serf's (don't own the book) or Noble's (couldn't be bothered to look it up) parma, but...the other one. :slight_smile:

Re: the form requisites - yep. That's why I'm referring to the /5 Spont version of it. Basically you're making it up on the fly. And I tend to use low-magnitude Intangible Tunnels (described below) to add range for spont magic, so regardless I usually design any effect for Touch.

Have that in a lesser enchanted item (such as a ring), and it adds range automatically to your low-level effects. A similar effect with Maintain the Demanding Spell (ReVi) adds duration to D:concentration spells.

13

No, that would be the Serf's Parma [url]Serf's Parma - #7 by Ravenscroft].

Monk's Parma (IIRC) is when you left your books at your workplace but are not currently there.

Sorry to contradict you, but having this effect in an item is slightly more tricky. The Item is the caster, not you. So even though you know the Tunnel is there, you have to sense it in some way in order to use it.zz

14

Adding range to a spell is a MuVi effect, not a ReVi effect, and you can't make a magic item that casts MuVi spells except on spells on the item and you can't cast MuVi spells on Spont spells.

15

That is correct. This effect does so indirectly: it creates a magical tunnel that you cast through, rather than modifying the spell itself. It's one of the basic guidelines under Rego Vim - the proof of concept is the Intangible Tunnel effect, which uses the Arcane Connection range. The one I describe uses Sight, instead. (EDIT - admittedly, you have to have at least R:Touch on the spell to get it to work.)

The benefit being that you can cast spont magic down it with no difficulty. Which is to say - it's a really freakin' useful effect for spont magic. These kinds of variations are discussed in the Hermetic Projects book, in the Wizard's War (Invisible Assassin?) chapter.

(Similarly, Maintain the Demanding Spell can maintain a spont/5 concentration spell without issue. Which makes it ALSO incredibly freakin' useful for spont magic. )

16

Personally, I'd make the intangible tunnel require "group" target, as it's linking two things other than the item itself.

17

Ack, what ate my post?

Having an item cast an Invisible Tunnel effect does not, in itself, allow the one controlling the item to perceive the tunnel, and as the tunnel can't be perceived it can't be targeted by the Spont spell.

18

You need some effect to sense it, although touch is valid. Or taste if you lick the ring.

19

So, I went back and researched this - and yep, according to both AM5th and HP, if you're not the caster you do need some sort of supernatural way to sense the tunnel if you want to use it (Just Per+Magic Theory doesn't cut it) - however, both writeups are also clear that anyone who can perceive the tunnel can use it to cast, in either direction. So I don't think there would be any need for any additional modifications.

Conceivably, the spell itself could have an imaginem requirement, to let folks know EXACTALLY where it is at the user's end - unless the "need to perceive it with magic" is necessary due to the "magic" part, and not just the "perceive" it part. In which case: no, you need to perceive it with magic in order to use magic on it.

Also, as Lamech mentioned, you could use a Taste-based effect to lick the ring (Taste the aura of magic: InVi 10: Base 5, Range: Taste, Duration: Diam +1), although a touch based one (InVi 15) would probably be more useful. Although "kissing the ring" to use it does have a certain flare to it...

So while this isn't an issue for the character that developed these rings in the game I play in (ReVi expert, who has Sight of the Active Magics running whenever he's doing stuff like this), it does pose an additional level of study for the other characters who may want to use this.

Of course, interestingly enough, it also places a level of protection for whoever is using it - the tunnel links the caster to the target, not those who use the tunnel. So anyone who casts back through the tunnel will hit the ring, not the magus. To affect the magus, they'd have to use a Group or Room effect (as per the Intangible Assassian chapter - to affect anyone touching the caster, you need to use Group). Which may not help much vs. a pillum of Flame, but will certainly protect against, say, Corpus or mentem effects.

20

Absolutely, and a very good point