# The oak limb - Enchated device - Are my maths correct?

Hello,
I have designed the following device for one NPC of the saga and, although I have checked the figures three times I still have the feeling that something is not correct. May I have the advice of those venerable masters of Ars Magica that oversee the forums?

The oak limb

This magical device is an exquisite piece of wood resembling an arm. It has a small bone engraved in the palm. Powered with herbam, corpus and mentem effects, it allows the owner to replace his natural arm with one made of wood. Of little use for the average magus, it is invaluable for one that has lost one her arm as it allows her to grasp and handle things almost as if it were a normal arm. Even spells can be cast although with some difficulty

The oak limb is attached to the remains of a severed arm where it roots and feeds from the bodily humours of the target. From that moment the device is ready to receive mental commands from the target and to move upon his command. The limb is designed with joints that allow the basic movements of a normal arm including fingers and wrist but its movements are clumsy, imposing the same penalties than the Clumsy flaw.

The device has three effects instilled:

• Perception of the mental command (InMe 30): This effect allows the device to read the commands issued by the caster. (base 15 + 1 level for touch range +1 level for concentration duration +5 because the device maintains the concentration)
• Movement of the built arm (ReHe 12): This effect moves the joints of the wooden arm to simulate the normal movement (base 3, +1 level for concentration duration, +5 because the device maintains the concentration, +3 because is linked to Perception of the mental command)
• Sustenance from the broken body (MuHe (Co) 15): This effects allow the wooden arm to feed from the bodily humours so it does not die (base 3, +1 level to use the bodily fluids; +2 level for sun duration, +2 two uses day, +3 environmental trigger)

Building of the device:

• 9 pawns to open the device. 6 from the medium size wood used to carve the arm plus 3 for the tiny size bone engraved in the palm.
• 3 pawns of intellego or mentem vis to instil the Perception of the mental command effect
• 2 pawns of Rego or herbam vis to instil the Movement of the built arm effect
• 2 pawns of Muto, herbam or corpus vis to instil the Sustenance from the broken body

Thank you very much in advance.

The sustenance is really cool, but unneeded. Why does the arm mneed to be alive at all?

THe perception bit needs A LOT of penetration to beat the magus' magic resistance. otherwise the arm will hang limply, since it will not receive any info from the brain (blocked by parma). Being connected to the arm of the magus can offer some nice penetration multipliers, but you will still need to invest some penetration on the device

Cheers,
Xavi

I'd assume the effect allows it to heal and renew itself from wear and tear. Long-term thinking.

One thing to be aware of: if you don't forget to turn this thing off regularly you'll gain a point of warping annually for being under a constant mystical effect (the InMe effect). The permanent 'stuck to body' effect -may- have a similar result.

Of course, the mystical warping for such a thing is just part of the flavor.

Very nice. Has a cool flavor to it.

Note that the only way in-cannon to avoid the warping is to have such functionality bestowed through the familiar bond. A Cr(Re)He effect growing and controlling hand, perhaps. Far less cool. You might want to consider allowing a talisman to do the same, perhaps as an exception through some Mystery or whatnot - so that if this arm is his talisman, he would incur no excess warping from it. Alternatively, just suck that warping up - it's great flavor.

I often maintain that a magus can lower his resistance to make such items penetrate his MR, and as long as the item is kept on it will continue to work even as the MR is renewed. I'm not sure if it's strictly RAW, but it allows magi to more easily use rings and such. So under these house rules, no penetration would be needed.

TMRE has "the body as Talisman", so if you want to go the Talisman route, that might have some hints.

That said, I think the arm as a talisman would be even more cool than it already is!

The perception effect looks to be taken straight from the linked trigger description in the book (page 99), which also points out that the effect can be resisted but the wielder can choose not to resist. So no penetration needed.

You seem to be missing effect frequency / constant effect modifiers except for the last one.

I would say the sustenance is a CreHe (MuCo) effect - base effect is level 1 keep it growing well, not becoming sick, with Muto and Corpus to let it get sustenance from the user. I would give a magnitude or two reduction because of the Clumsy and needing food (sort of like a necessary condition for the item).

And like someone said, I'd look at the mysteries rules for incorporating unnatural elements into your body and use that as a guideling for having this cause warping.

Question - once it is attached to a person, is it enough a part of them to be affected with corpus? What happens if someone polymorphs this wizard?

The device was created this way for three reason. The first reason was physcological for the NPC creating it: He does not feel comfortable attaching himself to something dead. The second is a practical one (as WolfOfCampscapel stated): So the wood does not decay and renegerates in a similar way a living branch will do. The third one maybe was a mistake from my side: If the limb was part of the body I though it could be considered part of the magus and, thus, it will be possible for him to touch things with the limb and delivering a touch range spell.

Actually my thinking was in the same line than:

but I have to confess the description does not seem that clear to me now. Specially after rereading the rules for Magic Resistance where it says any touch spell, even casted by the own magus, need to penetrate.

Hmm. The magus has both arms replaced by oak limbs. You can only have one talisman, so I did not want to have different rules for each arm. Being said that, I will investigate TMRE for additional ideas.

My thinking here was that, as the device maintains concentration, you only need one use per day, that is +0 to the spell level. Sounds that ok?

I went for a MuHe base 3 for the change of the plant required and considered the Co requisite only to allow the transformation of the bodily humours so they can be used by the plant. I did not found a guideline to do so but, following the example of requisites laid out in page 114 (adding magnitudes) I took the easiest approach. Also, it uses the strongest Te & Fo of the magus.

I like your suggestion, though. That would make the effect a CrHe (MuCo) 4 (base 1, +1 magnitude to use bodily fluids, -1 magnitude because of the clumsy weaknes, +2 magnitudes for sun duration, +2 two uses a day, +3 environmental trigger). It would be cheaper to build!

I did not think about it. But I would say if you want to polymorph the magus you need an herbam requisite, like if he wanted to change his clothes. Otherwise I will say the corpus part of the limb will change allowing, thus, the limb to operate but it will remain as a human limb. What do you think?

Thank you!

I would happiluy accept the dual arms as a single compund item. It is your talisman after all, and talismans are supposed to be SPECIAL and COOL. Dual wood arms fit that criteria Same for penetration, but I took the opposite path It is not so clear to me now that it does need penetration. So maybe you can pass it over. In any case it is for a NPC, so you could have the arms being part of Atlantis or the true rulers of France and it would be OK Maths are not so important here. But yes, he will warp like crazy with those arms.

Cheers,
Xavi

totally agree with Xavi

Spells fail at sunset and sunrise.

The familiar examples have a lot of the concentration maintained once per day. The rules there state that you need to concentrate at sunrise/sunset on the effect to keep it active, but you can "restart" the effect once/day if you forget.

Totally agree.

And i also think there shouldnt really need to be penetration either...

Thanks for correcting me. It makes it more powerful than Sun Duration.