Spell Design: The Thread Before the Grimoire

Games Discussion Ars Magica
81

It's fairly clear from the RAW that a negative penetration is the normal result if the Casting Total does not exceed the Spell Level (and the bonus is not big enough to compensate).

The formula in RAW is: Penetration = Casting Total + Penetration Bonus – Spell Level

If the Spell Level exceeds the sum of the other two terms the Penetration will be negative.

Which is irrelevant if the target has no Magic Resistance, but means that usually the spell will fail to penetrate if the target does have a Magic Resistance. Although, conceivably the target might have a more negative Magic Resistance due to standing in a strong foreign aura.

82

After checking i see that you are indeed quite correct. Always just simplified to zero Pn instead of counting any negative. Might be half a decade since i read that part last time... :mrgreen:

83

I have abandoned this idea. Thank you again for the analysis showing it did nothing.

84

SO.... back to spell design, then?

I'll post some a bit later.

Vrylakos

85

Do you think this spell is ok?

Impetus Haematitis, MuTe level 4
R: Touch, D: Ring, T: Circle

Gives all sand in the target area one property of haematite (lodestone): it tends to move towards iron (and steel etc.) with a strength growing with the amount of sand (and iron) and decreasing with the distance. Importantly, the sand remains sand, so iron does not tend to move towards it (as it would if it were real haematite). The spell can affect up to ten cubic paces of sand, and obviously any sand that leaves the circle returns to normal.

Base 1 "Change one property of dirt", +1 Touch, +2 Ring

86

I can't see why it wouldn't work. However, I have not checked the base 1 you use. In fact I think it is a very good "neutering spell" for magi that want to impede enemy fighters, but not necessarily kill them outright. The ring/circle parameters are for something special?

Coupled with the infamous (around here) "create Diameter sand" Level 3 Tyrrellean spell it can be quite powerful.

Cheers,
Xavi

87

It's quoted verbatim from the MuTe guidelines (in fact, it's the only level 1 guideline).

Well, yes. The spell's not really meant to impede enemy fighters. It's meant to make cheap flying ships :slight_smile:

88

Hmm... I would have never guessed it. Would you mind explaining the process? :slight_smile:

Xavi

89

I tend to decide how much a spell like this can do , based on Unseen Porter = As per Str: +05.
Even in Mythic Europe i dont think lodestone is stronger due to mass more than individual size.
(feel free to prove me wrong) :slight_smile:
If for a fighter (or someone) significantly covered in iron/steel ,
then i would give a -03 penalty for a sand in the underwear type hindrance.

90

Uh? What I'm saying is that if you double the amount of sand, you double the amount of "pull" (i.e. every grain just pulls the same, but now you have twice as many).

91

Why stop there , you can get to the Lunar Sphere if it works the way i think you intend it to.
Even if you dont make a flying ship , using this type of spell ,
one to make the surface underneath you magnetic such that it repels the keel/hull of your ship ,
reducing drag(friction) and increasing speed could be amusing for your ST to deal with.

92

Can you find a spell guideline that indicates you can do this , not necessarily Terram.
Doubling Size does not double Str for Corpus.
In real life , does magnetism work like this , power increasing with mass?

93

Ok :slight_smile:

You need to build your ship with a (large) spherical chamber in the middle (with its centre above the waterline) capable of supporting the rest of the ship. We'll call it the propulsion chamber :slight_smile: For simplicity of visualization, imagine the largest ball you could fit in the middle of the ship, and imagine superman pushing the ball upwards from the inside: he must be able to lift it (and the ship with it) without the ship coming apart.

A magus casts Impetus Haematitis, tracing a ring on the perimeter of the propulsion chamber. Ideally, the ring has been carved or something, you really do not want it disturbed. This is all the magic you need. No enchantments, no rituals, just a simple spell than any apprentice can spont - cast just once.

Now you need a lot of barrels/pots/basins etc. with an iron (plated) bottom; each filled with sand. Like, a lot of sand. Within the propulsion chamber, the sand will push towards the iron, which has two effects. First, no matter how you turn the container, the sand will not fall off, because it pushes towards the iron bottom. Second, and perhaps more importantly, if you turn the container upside down, it will tend to fly upwards; if you turn it laterally, it will push laterally.

Just position enough containers on the ceiling - like you would normally do with ballast at the bottom - and the ship floats. Add a few more, and the ship rises. Remove a few, it descends gently. Move a few towards the front of the chamber, and the ship moves forward. Just make sure that the containers are solidly anchored to where you place them, or in rough winds you risk a catastrophic breakdown of the whole system. But then again, any sailor with ballast experience would be familiar with concept. It's just upside down.

I think the beauty of the system is that it provides adjustable lift and propulsion with just a single, low level, non ritual spell that you only need to cast once. Incidentally, the same mechanism allows you to make perpetual motion devices that provide mechanical power to the covenant where needed. One casting of the spell per device.

94

Well, two bricks pull down with twice the strength of one.
Two oxen push forward with twice the strength of one.
Two tiny lodestones push with twice the strength of one.

Note that with "strength" here I do not mean the "Strength" stat, but, if you wish, the number of pounds you can lift if your strength is applied upwards.

95

Nice. HOwever, what you need is half (or a third or something like that) of the sphere to be metallic, not the bottom of the barrels. Unless you fix the barrels to the sphere somehow.

I am not totally sure how you would remove some of the containers without them crashing down. You can cast a PeTe effect to cancel the effect of a single barrel, but that barrel will come crashing down immediately, probably smashing in the process. I can imagine the sand working like a submarine easily enough, with some columns half filled with sand and metal at the top. You would enchant as many columns as you need to compensate for side movement and rise or come down, but they would not provide propulsion. Well, you can always use horizontal columns for that. All columns wouild be round, of course.

It is an ingenious system. Quite open to sabotage via WOMS, but easy enough. I still prefer a target:structure Herbam spell, but this is an ingenious system :slight_smile:

Cheers,
Xavi

96

I'm not convinced this is how it would work. If you fill an iron-bottomed barrel with magnets and turn it upside down, sure the magnets will stick to the iron "bottom" which is now on top, but it won't make the barrel tend to fly upwards.

I see you're trying to fix this by specifying that the iron doesn't move towards the sand (that is, the iron doesn't move towards the magnets in this altered example). But magnets try to move towards the iron, not through the iron. Once it's touching the iron, there's no reason for it to move any more (particularly in medieval paradigm, I think).

I like the creativity though! If I were in your troupe and counterarguments were marshalled against mine, I'd agree just to ride the sandship.

97

Thats as may be , i dont know enough real world physics to prove otherwise using effective methods of applied force or gravitation/magnetism ,
but in Ars Magica Aristotelian Paradigm , a ton of bricks falls faster than a ton of feathers.
A greater element of earth in the bricks than the feathers , if i have it right.

There is no Newtonian Force from your muto lodestone propertied sand.
The sand rises to the limit of the spell , but provides no actual push (no Rego component).

98

No, no. The containers will "fall upwards" if you turn them upwards, because the sand pushes towards the bottom. So they will just rest upside down on the ceiling. You might want to "attach" them more strongly so that they do not shake, though, I agree. If the ceiling has "bumps" in which you can rest the containers it should be enough (it's really the same problem as securing ballast at the bottom).

What you need is containers small enough that, individually, will not "pull" more than, say, twenty pounds. You can just pull them down with a gaff (a hook attached to a pole). Again, it's the same principle you use for ballast, but upside down.

Just use buckets instead of columns! It's simpler and more adjustable: you need to descend, just remove a bucket from the ceiling and put it on the floor. The sand will push towards the iron bottom no matter the orientation of the bucket. Remember, you do not need to enchant the buckets individually, the Circle effect will affect all the sand within the chamber.

That's very, very true. On the other hand, the kind of opposition that can put up that sort of attack can also probably sink a normal ship at sea without too much trouble, so...

In any case, partial protection could be provided by a highish level PeVi Unraveling the fabric of Vim, with Ring Duration and Circle Target, which keeps away from the propulsion chamber any Vim magics up to Level of the Unraveling + 5 + stress die.

99

That's exactly it, no Newtonian action-reaction principle in Aristotelian physics! This opens up a lot of free energy :slight_smile:

Ah, the first thin layer of sand may not push, but all the rest of it will.
Even were it as you say, you could just "insulate" the iron with a thin layer of cloth.

We thank you for choosing Hermetic Airlines :slight_smile:

100

Real world physics need not apply.

I think it is fine with Hermetic magic to give the sand the property that it moves towards the iron, but not also give it the property that the sand causes iron to move towards it with equal strength.

The trick is that the force making the sand move towards the iron is stronger than the gravity force downwards of both the sand and iron (and the rest of the pot)--- so there is a bit of upwards force left over to combat the downwards force of the ship. Get enough of them in place and the boat will float, more and it will rise. Although it is not quite the same, it is not too dissimilar to the bouyancy arguments which explain in the real world why a hot air ballon works.

I would question whether you can give sand this special property with the base 1 guideline though. It seems like it should be using the Level 4 "change dirt so that it is highly unnatural", guideline --- which increases the magnitude of the whole thing a bit.

Otherwise, this is a nice idea.