This has come up in our saga, and I have seen mention of it in the books...
If you have a captive Magi, how do you prevent him from casting spells??
I know you can do the following things to handicap him:
...but these things don't STOP a magus from casting a spell...
Any ideas?
Salvete Sodales!
The best way to counter magic is to use magic: Turn the prisoner to stone, put a long lasting sleeping spell on him or work any other ReMe-effect that keeps him from using his power. If that magus' Parma is too strong you either have to wait for dusk/dawn or 'convince' him to let it down (e.g. by poking him with a mundane sword)
If by any chance your Grogs catch a magus without one of their masters at hand they can try the old 'club-on-head-method', but repeated use might cause permanent damage.
However, you should be very sure that your captive has commited serious hermetic crimes (or that you are engaged in Wizard's War with him), because otherwise you will be in big trouble at the next Tribunal meeting. Actually you might be accused of temporarily depriving him of Magical power (cf. HoH:TL, p.46).
I hope I could help.
Vale,
Alexios ex Miscelanea (aka Lars Gerlach)
IMO, using magic to counter magic is to to expensive. Having bound and gagged the magus, simply hire a grog to torture the bloke. Distraction will keep the magus from casting spells and the covenant torturer will get earn some extra exp.
To reveal the darker side of our campaign, the last magus we captured we cut his hands and tongue out, why take chances? He turned out to be a diabolocist so everyone was cool our decision. Currently the magus is still being tortured.
Tuura: 
Yeah, thats the situation. The fella in question was trying to open a gateway and let loose the Demons on the other side. He was the only one of his group that survived our intervention (of the four). It was rather rough on us...and expensive. I think we used up about sixty pawns on that little 'party'. With such difficulty, you can understand why our group is a little nervous about holding him...
(The ironic thing was that there was a group of Diedne studying the site, and they were 'turned in' by these guys, because they were close to uncovering what they were doing)
Alexios ex Miscellanea: Yeah, we kind of did all the mundane stuff already. None of our group really specializes in those things you mentioned though...and there in lies the problem... :
I do like the torture thing though..what kind of negatives would that give? I imagine this would require 24/7 work though....gee, I need three guys to inflict pain...
This is a good point. Our campaign often has a heavy political element. The leader of our covenant was in his right to out right kill the offending magus because the man was a proven diabolocist. He chose to torture him instead because wanted to establish that this crime deserved a punishement greater than a quick death. He also wanted to establish a reputation for the covenant as strong and 'tough on crime'.
He suceeded in these points, but he also gained a reputatations as "Torturer" and the moral of the covenant went down as they knew this guys is being tortured essentially 24/7. The population of the covenant has become more fearful of the magi because of this action. So while Heremetically we look stronger, internally we are weaker.
I believe the Covenant book has some rules to deal with this, but currently we are using common sense to detail the reprocussions.
And if you chose to follow this route and don't have a torturer. Don't worry trial and error is considered torture. So after a few days of trial and error your covenant will have an official torturer or three. 
In one of my sagas a Verditious PC was forced to spend seven years in service to the Quaesitores (in stead of being killed). One of the things he made were manacles with PeVi effects in it to use on magical prisoners.
Roger...yeah something like that has been floating around in my head for a LONG time. The problem is I need the time to make them...
Hence the question....
Tuura:
Would it raise the moral of the Covenant to know he was slaughtering children and loosing Demons? Having morality problems with certain issues tends to end when it hits home...ie its YOUR child, or the dump is going to be in your back yard...then things change...RL has proven this to me many times.
In this case we have the children living in the Covenant...plus, they won't hear or see a thing...the walls are VERY thick.
There is a perdo vim guidline that lowers any casting total by a certain amount.
There is a perdo vim guidline that cancels any spell with a certain casting total or less.
Assuming that a magus could be chained up until their parma lapsed (so penetration would not be an issue), then these two spells in combination and at a high enough level (perhaps coupled with other restraints) could keep them under wraps.
Kill him.
(That's almost certainly occurred to you, so I assume that by asking the question you feel you have a reason to keep him alive for a while, at least. Nonetheless, keeping a diabolist around is dangerous. Are you really willing to take a chance that his guards won't make mistakes or other diabolists/demons won't try to rescue him?)
Nathan
Great idea (and yes I thought about it), but I need him for a bit....
Well, I don't plan on keeping him around long...long enough to get what I need from him, then I am going to feed him to the Merinita's dragon...one piece at a time... I was thinking about cooking him a bit first...Animal or Olive oil???...hmmm, Well since I captured him about 2000 miles(?) away in Thebes, Olive is a much better choice IMO.
As for other Diabolists trying to rescue him...I certainly HOPE they try. That way there, my report to the Quaesitors will be much more complete. I seriously doubt they will though. We cleaned up the site of his capture really well (even washed it down..hehe), and we certainly weren't local. If they try to use an AC to find him, well, he is inside the Aegis...plus we killed all his Friends and more importantly, his leader. Now if his leader's leader shows up at the gates, then that would be extraordinary, and would attract a lot of attention...I think their methods would be a little more discrete though...and that won't help him soon enough.
(...and if things get too rough I suppose we could retreat to the one tower we have...Level 10 Divine aura..that should keep out the pets...)
Erik: Yeah, but from my memory, and your reference, you would need to KNOW those spells (not spont)...I was thinking along the lines of thumb screws on his reproductive organs, or Faerie lice in his hair..that kind of thing...
Something that is quick and easy....and takes little planning...
Consider how difficult a spell it would need to be to open a set of manacles or undue a bit of rope used to tie this individual.
This is a regio spell of minimum level ( like 3 ). You are going to need a really good Aegis to prevent a spell like this from working. Since the maximum spell without a ritual is a level 50 then you would need this type of Aegis to prevent this spell ( if the magus has some levels of ability in these areas ).
A level 3 or 4 spell base in corpus magic with maybe a level or two for duration would give enough for the magus to overcome negatives of torture ( giving a +6 or +9 modifier to concentration ) that they could then work on other spells.
A level 4 Dance of the Staves will usually be enough at that point to turn the beating instruement back on the grog.
If the magus was backed by a powerful lvl 50 magic might demon ( like Bartholomew ) then most of his abilities will get through anything less then a level 40 Aegis and could still know what was going on up to a level 50 Aegis.
Holding a mage is very difficult to do if they are a young mage and an archmagus is almost impossible if they are free to think.
Also consider the interesting virtue Deft Form that makes even the loss of tongues and hands no problem for the caster with this art.
Other troubling abilities include supernatural talents that don't involve casting spells like Entrancement ( the grog that was supposed to be watching the magi now is his puppy dog and telling him all the secrets of the castle ). Another talent is shapeshiffer that could change shape to free themselves of bonds.
Then there are good old methods like bribery which if your grog was a former outlaw or bandit might happily accept especially if they have not received any special reason to stick with their current covenant. It only takes one of the grogs that are watching the captive to decide that ten pounds of silver and a ticket out of the covenant is the best deal they are going to make in this life time.
Ah, well... If you've been working on dismantling the Organization, that should give you an edge. Remember, though, that to track someone via an arcane connection, you don't need to be able to pierce an aegis, you just need to be tracking the arcane connection when it disappears into an aegis.
I ran a diabolism adventure in which a group of diabolists had decided to kill magi for revenge and profit. Their problem, of course, is that they didn't know where to find magi - as in your case, the magi who'd angered them weren't "local." They had managed to get their hands on a Hermetic tractatus, however, and used it as bait to find magi. After assigning a small demon to watch the text, they put it into circulation via a local bookseller they'd compromised. Their (correct) assumption was that the tractatus would eventually find its way back into the hands of magi. So, when the demon returned to them and reported, "I followed the book until I came to such-and-such a place at which point some magical force prevented me from proceeding further," they knew they'd found a Hermetic covenant.
Of course, if diabolists do this in your saga, they may not find the players' covenant. In which case, diabolists might start taking revenge by whacking magi in another covenant - with possible legal repercussions if it was discovered that your players had provoked this.
Nathan
It's been suggested you kill the guy and to this response was, "I need him a live for a bit."
I'm curious why. As GM, my least favorite element about Fantasy games is the ability of characters to "Kill first, ask questions later."
Despite my distaste for this element it's a standard of Fantasy and exists in Ars. So why don't you kill the guy and get the information out of his ghost?
Urien asked:
Probably not. But how clear cut are the circumstances? Any diabolocist that is so blatant as to wear black, hang with red skinned demons, and shout 'satan, satan, satan!" is likely to win no followers and earn no souls for Hell. Certainly this cliche is great for a clear cut bad guy, but if the diabolocist is say the leader of a church, well recieved in the community, but is teaching corrupt lessons and having people worship false saints. Then Yes, killing him is going to be a problem. So the answer is dependant on the situation.
Again. I feel this depends. Certainly if the family is involved there are going to be strong feelings. But lets say you've been slighted and someone in your family rights the wrong. Lets say the knock the guy on the chin for you. Everything is even. But what if the family member puts the guy in the hosiptal. Is everything even, or are you now distrubed by the retribution your family took? What if they took the person home that slighted you, stuck him the basement and turned him into a project. How are you going to feel about that?
I point these out simply to say that while there is truth in what you suggest, the moral problem need not end simply because the home was assaulted. Not to get to political but consider 9/11. Many numerous people were killed and more families were irrepariably harmed. Yet not all of these people want or support the current war on terror.
One can explore moral problems however they wish, but it's a rare situation that leaves me suggesting one simple answer.
Well this is a great way to temporarily solve the moral crisis. However on some level this is essentially a dark secret. Should one of the torturers slip, the children, or their parents could develop a new view of the magi. Not only do they torture people, they do it secretly. If one decides to cover up questionable behavior thats fine, but in terms of good story telling I feel their should be consequences for that action. Those being either the secret is discovered, or constant effort must be made in order to maintain the secret. Then again, anyone see Match Point? Hmmmmm.
Tuura:
Experimentation..."He's no good to me dead...", and information. Since the things I will probably be doing are in a dark area as far as the law goes, this guy is the perfect subject...I can do anything, and nobody will care.
His Ghost is beyond that little bit of handywork. After I am done with him, I will bring back his Ghost to get more out of him....
Well, he slit the throat of a child of about four years old...while we were watching them perform a ritual (with Grogs and Companions). Of course our reaction was immediate...we attacked.
I agree with everything you are saying..but this isn't going to be a long relationship. One and done. I will (with a little help) be overseeing him, so the Grogs won't have much of a show....or tell for that matter.
As for the Grogs morale...well, we spend a LOT of time and effort keeping them fat and happy...plus, one of the Grogs was killed by this guy, and I used a magical device to resurrect him 
ncl:
If you traveled by mundane means, certainly. We did not bring him back that way.
Ah, but they destroyed another Covenant before we got involved. Okay, so they reported a house of Diedne mages investigating their secret, and were worried their "spot" would be revealed. The fact that these guys are Diobolists tends to put some serious doubt on their claims about the Covenant. 
(none were captured or found)
...So, from a Hermetic standpoint, they struck first...
PhiliAtlas:
Deft Form.
He showed no such ability while we were fighting him. I tied his tongue up during the fight, and it really hurt him...I also put a hurt on his hands (again with magic), and that made his situation worse...
I figure mundane restraints and and those two spells Every day are going to take care of that part of it...plus with me working him over, that will eliminate 12-14 hours a day where he can work magic....My sodalis is Nocturnal, so I can have him watch him while I sleep... and of course I have a Familiar and two apprentices...
Also, if he is wounded, doesn't he get additional negatives? I figure "Bind Wounds" will keep him alive and prevent him from healing...and still leave him with those negatives...lets see...
IIRC: One Heavy wounds...-5
Two Medium wounds...-6
Five Light wounds...-5
so added onto his -32 for all the other stuff (small assumptions), thats -48 to his casting total...I think the predominant spells he used were Creo\Perdo/Ignem, and IIRC his highest CT was about 50....so I guess a few more light wounds (unless he took some more from the beatings the Grogs gave him) should just about take care of that..
Wow. Thanks guys...you helped me think it through a little more and there it is. I am still not 100% on it, but I think a few more "tricks", and I will be able to start the fire for the oil...
Of course if he has Bartholomew on his side, then I already had a problem... 
PhiliAtlas: what is a "regio spell"?
Def'n Regio: Phili typing too fast and not proof reading Rego.
What about the infernal attention your torturer may receive from his cruel acts?
Perhaps the demon the diabolist was worshipping may think he has discovered another, more powerful pawn... you!
Only if you enjoy it I suppose. ?
Then again, any demon could take any violent act as an opportunity...say killing your opponent in combat, Certamening another magus over a Vis source (greed), studying a book instead of joining the crusade or giving your time to help feed the starving masses (selfishness)....Which is of course forbidden by the code...does that make the OoH Infernal?
Of course, it is only a possibility... a continuation of the story of the diabolist... after all, IMHO torture someone (no matter how evil he is) would probably attract much more attention from the infernal than delivering food for the masses...
Regards,
Bras