I'm not sure if I have already asked this in the past, but this is a recurring question that I wonder about quite frequently.
In Ann Leckie's Ancillary Justice novel, trying not to do many spoilers, there is an AI which controls thousands of dead bodies. The IA act through them, uses their senses, talks (and sings) through them, and they share its consciousness and self awareness. And I wonder how that could be replicated in Ars Magica.
So can you think of ways for someone or something to possess a large amount of bodies, being able their bodies and senses, with his/its consciousness being shared between them?
An hermetic solution would be wonderful for a necromancer. A non-hermetic one could make an interesting iteration of Damhan-Allaidh.
It seems to me that there's no real barrier to any part of it except the "shared consciousness" thing. Magic can puppeteer corpses, use their senses, and so on already. It's not even especially difficult for a specialised hermetic magus.
The real hard limit is the fact that anything really fancy requires the controller's attention and concentration. Without it, you're limited to the equivalent of "Awaken the Slumbering Corpse" (i.e. "Commands have to be very simple, like 'attack anyone who comes through here.'" - from the spell description.)
It's possible to concentrate on two things at once of course, but the difficulty jump in concentration rolls for doing so is so big that it makes even two at once quite a feat. Three plus would seem to be impossible using normal human faculties.
It's also very possible to have lots of bodies puppeted like that and switch between them so you only focus on one at any given point, but that doesn't seem like what you're going for.
So imo this breaks down to "can a magus improve his ability to multi-task so that many effects can be concentrated on at once?". Which is an interesting question but not one I can think of an immediate answer to.
A starting point might be using some clever mentem spells to monitor the mind of the corpse (assuming it can continue simple tasks without focus, as per existing animation spells) and only alert the controller when a decision needs to be made, so they don't have to focus on the full senses of every corpse at all times.
I would start with Inmost Companion (ArM5 p.149-150), as that is a canonical spell that allows you to simultaneously control multiple bodies. It's unfortunately lacking in details, though. Argentius is correct about concentration difficulties, with the added note that when a spell specifically lets you control multiple bodies like this is also falls under the rule
I think there would also be something of an exception to when the group acts together- for example if you possess a 5 "man" military unit, then fighting as a unit should only count as concentrating on one thing, while setting up camp with a division of labor (dig a latrine, set up tents, collect firewood, etc.) would require a shifting or distractable focus.
This is a very good point, I had forgotten about that spell (I don't think I've ever seen it actually used in a game).
From a certain point of view it might even imply that there exists a MuMe effect to do exactly what @Ouroboros is talking about. If nothing else you should be able to do a two body version, right? Just make an "Inmost Companion" type spell using a Corpus requisite so it gains human shape instead of animal.
Although even then I'd still say you run into the problem of the human mind being limited in how much it can multi-task. The spell doesn't explicitly say so, but that seems like the common sense interpretation to me.
A more sinister approach might be to make the bodies into revenants or enslave ghosts or spirits to inhabit them, using some very complicated mind altering effects so that the controller has access to their senses and can command their behaviour. On the upside it makes the bodies far more able to function and complete complex tasks without the controller dictating their every move, on the other hand that autonomy might not be a good thing considering they'll probably despise the controller for enslaving them.
I would actually suggest something along the Presence power of a daimon. A powerful enough spirit of Corpus might be able to manifest and imbue a horde of bodies. And a powerful-enough necromancer might be able to gain this Power through various means - as a Gift from the daimon, by being its spirit votary, by ascending and becoming such a spirit, or so on.
Living ghost would, to me at least, be the most interesting and involve the character being in play- it would also be useful on the "puppet master mage" idea as a way to overcome the limitations of its haunt.
One 'easy' way is to add Complexity to a spell to provide it with an in-built capability to aid the caster in controlling the additional minions connected to the spell. That said this seems a very saga-specific option.
The issue being that that is exactly the idea: to be able to control and use full senses of every corpse at all times
I agree with the concerns that Concentration is an issue. I guess it could be worked around with some CrMe to increase concentration beyond its human limits. Also, reading that other topic about Memory Palaces had made me wonder about something similar but to expand not memory but awareness and concentration.
I agree with @Argentius, that's a spell I always forget about and never had seen in play, and its a fantastic spell.
I like that. A lot. I'm not worried about the corpses feelings anyway. The spells or powers for all this would be high enough that a ReMe to tame that anger would probably be trivial in comparison.
I think that should be the starting point of the concept for a non hermetic NPC antagonist, indeed.
...and that would be the starting point for the hermetic version.
Not really worried about that. The idea would be to use this for an antagonist: game balance isn't really something I'm worried about. Still I want the numbers to add up and keep things inside RoP:M rules. And also keep that thing I really love about Ars Magica, which is that everything you see is something you can (most of the times, at least) replicate with enough dedication and power.
So the idea would be a Daimon with something similar to Presence, with a power similar to Inmost Companion that makes it able to take over corpses using their senses and controlling them, with an extra power similar to Memory Palace, which expands the consciousness of the creature. And try to keep it all under the rules so an hermetic magus could replicate it by becoming a Living Ghost.
First: daimons can create multiple aspects (in different places), but if I recall correctly a daimon is not constantly experiencing what every aspect is experiencing - instead, it simply reintegrates those experiences upon dissolution of the aspect. It's not very different from creating a sentient creature and eventually thoroughly probing its mind immediately before it is destroyed, which is something vanilla Hermetic magic can already do.
Second, note that The Inmost Companion turns a Mind (i,e. Mentem target) into an Animal plus a Mind, not into a Mind with a secondary, independent Mind. So it does not quite "duplicate" everything.
Third, note that there are powers (see LotN p.101) that turn a creature into a swarm of vermin, whose components while independent do act in a somewhat coordinated fashion. These are not Hermetic effects, but there is nothing in principle that disallows this sort of effect to Hermetic Magic. Exactly how "aware" each element of the swarm is of other elements is subject to debate, but note that it may be a moot debate - from an external observer's point of view it's kind of irrelevant if a swarm experiences unity or not, as long as it acts in a unified fashion.
Fun fact: I read somwhere that an octopus is effectively a swarm intelligence in this sense - each tentacle has its little sub-brain and the central brain only receives a rough sensory summary (and can impart rough commands) to the tentacles. Imagine you saw your arms, and you could will to them "grab that cup", and you'd know mostly by seeing that the cup is grabbed, but you did not really feel that you have grabbed the cup.
The issue isn’t that daimons can create multiple aspects but that many have the Presence power that allows controlling the environment including sensations of the area and of individuals in the environment. Not sure exactly why daimons were mentioned rather than genii loci (which can be either daimons or airy spirits). Different aspects of the same daimon can’t be within a mile (or something like that) of another aspect of itself anyway.
Oh, I see now, I was confused because not all daimons have that power, nor are they the only ones with such a power. However, this raises another issue, related similar to the swarm-mind issue. Can a daimon be simultaneously have the full consciousness of thousands of wolves at the same time, or is it more like ... projecting a common sense of purpose and receiving a feedback summary, the way an octopus (by modern understanding) does with its tentacles?
Daimons are, in effect, the magic version of pagan gods, and as such their abilities are not bound by human limitations like singular consciousness. In fact a daimon already has the power to create and then absorb multiple aspects simultaneously giving it multiple independent existences before the presence power is even taken into consideration.
One idea I haven’t seen touched on is a Muspelli with Valgaldrar. You can give the animated corpse a group corpus version of inmost companion to create a (rather dumb) undead necromancer that has the control and full senses of every corpse at all times, without having to worry about petty things like sleep or most distractions. The animated necromancer could be either a lieutenant of the Muspelli, or created with lifetime duration by a long deceased Muspelli, endlessly working to complete the unfulfilled orders of a (metaphorical or literal) ghost
Having thought about it a bit more, there might be a weird version possible for Merenita magi with Animae magic.
It allows you to make a faerie which is (mostly) human in appearance using a corpse, or to create an intangible faerie in the mind of the target. There's also the weirdness of what happens when you use Animae magic on your own reflection or shadow, where the resulting faerie can know things only you should know and be influenced by your personality.
If you could make the right animae and convince them to play along you could do some interesting things. Easier said than done though, and animae magic is a little vague about how much you can define the outcome.
Sorry, my bad. My current (on-hiatus... too much work....) saga involves lots of daimons, so that was on my mind.
I play it conservatively - allowing the daimon to generally be consciouss only of one place at a time, and to be only vaguely consciouss of everything else in his Presence. I've compatred it to my players to a person feeling his skin - you're generally not aware of it, but can see/focus on a part of it at wiill, and if something major happens there (like a huge Magical spell going off...) you're sure to notice and focus on that region.
This gives PCs more leeway to sneak around the region, while giving me free reign to have the spirit focus on them when it suits the saga.
