Magic Item calculation - it seems like cheating :)

Hi All,

My magus plans to enchant an item based on the errated Container and MuTe size-changing/shrinking magic.
I was shocked after doing the calculation. Is it right at all?

All-Swallowing Bag
MuTe lvl 39
Base 4, Personal, +2 Sun, +2 Room; +1 req. He, An, Aq, Co, +1 increased shrinking effect, +1 to effect stone - +3 linked trigger (Sun), +1 2 uses/day

The All-Swallowing Bag is an item of true wonder: when you put something into it, the size of that thing is decreased to 1/10 000 of the original mass/volume of that item. The size of the item is decreased to 1/21,5 in every direction (So a 21.5x21.5x21.5cm object is now only 1x1x1cm). The bag is made of calf leather, embroidered with red marks, ca. 1,2 m tall and 0,6 m in diameter. It has a strong and comfortable shoulder strap, also made from calf leather. The whole capacity of the bag is 283 litre - that means it can easily contain 2 830 m3 of original non-living material. Although it cannot effect living targets, but it can swallow even stone or human bones. If it is full of grain

EDIT: Item rewritten based on suggestions in this thread.


To affect most objects, you'd need An/He requisite added to the enchantment.

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Yes, I calculated +1 magnitude as req. to cover requisites for other than Terram (He, An, Aq, Co). The end result seems to be staggeringly high - that is why I as for a review.

Can you point me to this?

I'm not sure you need 50 extra uses per day, only 2 (the effect being applied to anything entering the room, and ending when something is removed).

MoH includes a +1 complexity on the spell Locked Storehouse (decreases an entire structure and it's contents). Not sure what that is about, since later in the same book we have Convenient Storehouse, an effect on an oak chest that does pretty much what you want, without the +1 for complexity. Convenient Sorehouse does include a +1 for "excessive size change", however.

Otherwise, I don't think additional mags for every requisite are necessary (but the +1 for all of them seems fair to me).

Note that you might find it hard to retrieve a particular item from the bag.


Base 4: [GUESS: Change dirt so that it is highly unnatural, I]
Sun +2 -> Level 10
Room +2 -> Level 20
+1 Requisite -> Level 25
+1 Size -> Level 30
+3 Linked Trigger Sun -> 33
+6 50 Uses per Day -> 39

Ok, I see a few areas for thought and rule interpretation. One, the idea is that this shrinks anything, so you have to add in requisites for stone +(1) and metal (+2), and noble metals (+3).

The rules about affecting noble metals, metals, and stone in the same spell are not clear to me. I would argue at least Base +3, another GM may argue dirt (0) + stone +1 + metal+2 + noble metals +3 = +6. If you want gems you would need to increase this to Base +4, and arguably a net +10 to affect all 4 types of Terram items. Lets be generous and say this calls for +1 complexity and for anything +4 to include gemstones for a net +5.

Second: Size, by base you can only decrease by a factor of 1/10. One instance of Size +1 increases this to 1/100 the size. Since you want 1/10,000, you need Size+4.

Third: Requisites, since each requisite added enhances the effect, you need an additional +1 per requisite added. You have An,Aq,Co,He, for +4.

Another consideration is that Terram, each have limitations of how much material can be affected, and all have different base sizes they affect.

Terram: The base Individual for Terram depends on the material involved. For sand, dirt, mud, clay, or similar substances, it is about ten cubic paces of stuff. For stone, it is a single cubic pace. For base metals, it is a cubic foot, while for precious metals it is a tenth of that. For gem stones, the base individual is one cubic inch in size.

I would argue that you may need additional complexity added here.

Recalculated total:
Base MuTe 4: Change Dirt to 1/10 mass
Affect Stone, Metal, Noble Metal, and Gems separately, = +4 to +10. We'll call this +4 to be nice: -> Level 20
Sun +2 -> Level 30
Room +2 -> Level 40
+4 Requisite -> Level 60
+4 Size -> Level 80
+3 Linked Trigger Sun -> 83
+6 50 Uses per Day -> 89

This is my take on things, at minimum. I'd argue for another +2 magnitudes for the sheer complexity, making this level 99. And at this point, I'd add in Unlimited Uses for another +4 levels at 103. In other conversations on the board I'm on the more conservative side of requisites, as the core rules are far too loosie goosy. The core rules state that every time a requisite enhances the spell, add +1 magnitude, and I stick to that.

Also 1/22 is too generous, I would argue 1/21.5, which cubed is about 10,000.

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Actually you need to include the +1 Requisite for each of the additions, which takes the level up to 54. You are expanding the capabilities of the enchantment into each of those, which meets the requirement for a +1 in each.

You also need to include Touch range. The enchantment is not affecting itself but objects placed within. That takes the level up to 59.

You need to include the magnitudes to affect a higher material for Terram, which would be +2. The MuTe section (ArM5, p154) clearly states that the modifier only applies once so it is +2. However Terram might not be the actual Base to use. You have to check the Base for every Form and use the highest, with that Form being the primary. At the very least this will raise the level to 69.

Size calculations are correct with the Errata. It used to be 1/10th, however that was changed to 1/100th for non-living things. How big an object it can affect is more limited by how big an opening is in the bag, since it is Room and thus able to effect up to 10 Base Individuals. That would be up to a 10 cubic inch gemstone at the smallest end of the range.

EDIT: Here is the Errata. Search for "Targets and Sizes (p. 113)" will take you directly to the appropriate section.


Thanks for pointing to the section of the Errata, Troy.

Touch range is not necessary. The spell is cast by the room itself (the bag), upon the room itself, the Target is Room (affects everything inside the room).

The Room is not capped at affecting 10 base individuals. Instead, a base Room is defined as "large enough to fit a hundred standard Individuals with some squashing". If the bag is smaller than a base Room for the Form item it may be enchanted w/o additional magnitudes for Room size. But it's interesting indeed to note that a base room for a earth/stone/metal/jewel is not all the same (since the base Individual for each of those has a different volume), so one needs to decide how to deal with that. OTOH, a base individual for metal is an 1ft cube, and 100 of these are a 3mx3m room, so leaving gemstones out should do it (these are usually pretty small already, why would one want to shrink them even further?).

Indeed, magnitudes for stone/metal/gemstone are necessary (and only the highest applies, so indeed a +2). But generally speaking, I don't think checking for every form is needed. This is using Terram in its capability of affecting solid objects. The base is for Terram, with requisites covering the specific type of object as required.

+1 for each Form is completely unnecessary. A +1 for a requisite is only needed if the requisite adds an effect. The requisites here only allow the spell to have it's effect (nominally, affect solid objects outside of Terram). Even the +1 for all of them that I called for is just gut feeling because I thought the spell too permisive, but it's not strictly necessary per rules. And even without it, getting a high enough Lab Total to enchant an effect with 4 different requisites is already going to be difficult by itself.

Toronus, was the +1 Size in the original spell to move it from shrinking by 100 times to shrinking by 10000? If so, I had interpreted it wrong. I thought you added it to allow you to shrink objects larger than a base Individual (for example, a block of iron with 1m x 1m x 1m). Consider changing it to "+1 increased shrinking effect". Thinking again ,additional mags for object size should be mostly unnecessary, so I'm not even sure why I though it in first place.

So the revised effect in my understanding should be:

Base 4, Personal, +2 Sun, +2 Room, +2 base metal, +1 increased shrinking effect, +0 reqs. He, An, Aq, Co, +3 linked trigger (Sun), +1 2 uses/day = 39.

I removed the +1 for multiple requisites I called for before based on my reasoning above, but I'd still add it if I were the SG, for a final of 44. I'd add it because while I don't think each requisite significantly expands the application of the spell, all of them together do so, and therefore at least a +1 is reasonable.

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I meant, the enchantment itself should be MuTe(AnAqCoHe) lvl 39, your Lab Total should suffer for those requisites. If you don't instill them, those objects won't be shrunk.

  • all Form are base 4 or less, you may want extra magnitudes for stone/metal
  • I'd almost go for free requisite, when I compare to MuCo guidelines
  • "Personal Range means that the effect targets the device only", I'm not sure what it means for T:Room here
  • +1 level for 2 uses per day is enough.
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@RafaelB, completely disagree on the requisite. Each added requisite adds a whole new class of objects that can be shrunk, therefore is an enhancing effect and must be added.


oooh a bag of holding. :slight_smile:

Let's take a swing!

I'll start with the MuTe Base 4-- that seems fair, with the change of dirt to something highly unnatural. Working off the MuCo example for Preternatural Growth or Shrinking and the base 4 option to grow to 8 times its size, I'll say it can shrink to 8 times its size. Clearly, this will require some discussion with my troupe, but it's not crazy

As per page 154, the change for metal/gemstone is +2, that gets us to 10 (Base level 4 + 2 magnitudes is 4->5->10).

Range will be touch-- we put the object in the bag, touching the lip of the bag. There's +1
Duration -- we can do concentration, the bag will maintain the concentration when we get to that point. There's +1
Target -- We're affecting an individual, but, we also want to be able to affect, say, a sack full of coins we put into this sack, so I'm going to go with the suggestion of Room, saying that the object must fit inside the mouth of the bag to be affected. The level of creative interpretation here is left to the troupe. That's +2

That starts at: Base 10 + 1 (Touch) + 1 (Conc) + 2 (Group) for a total of 30. But! we do want it to affect more than Terram, so we add Animal, Aquam, Herbam. If we want bones or corpses, we add Corpus, too, I suppose. Whether or not each one adds a magnitude will depend on the Troupe-- some could say that because the contribution is not cosmetic-- the shrinking of all things is part of the point-- we get to: 30 + 20 (4 magnitudes!), for a MuTe 50 base effect. Another troupe might say that we're already accounting for reducing metal and gemstone, we're comfortable with this effect in our saga and don't need to make this harder than it is, leave it at a MuTe30

Now, we can make this a lesser enchanted item, it only has one effect that works while the item is in the bag. We'll have to be able to do it in a season. This means the shape and materials used will matter here. Following the request, we'll make usable 50 times a day, so +6, and it maintains concentration for +5, that gives us a total of MuTe 41 or 61.

The trigger will be touching the object to the lip of the bag and saying "In you go." No linked trigger necessary.

This will require 5 or 7 pawns of vis-- 1 for every 10 or fraction thereof, and since we can only use Magic Theory * 2 pawns a season, we'll need a MT of 3 or 4 to do this. We can choose a Large Leather bag for our purposes; that gives a +5 bonus to "create or transform within" which we can take advantage of if our MT is 5, so we'll presume it is. EDIT: Leather can handle 2 pawns, and large size is x4, so the resulting 8 pawns is well within the 5-7 we need to do this and it makes it reasonably sized for putting bigger things in.

To do this in a season, we need a MuTe lab total of either 82 or 122. If you're requiring requisites, then you use the lowest art of the An/Aq/Co/He/Te set. If not, then just MuTe. Working with the 82 total, let's just spitball some numbers, and presume we've also made this spell:
Mu 15 + Te 15 + Int 3 + MT 5 + Aura 5 + known spell 6 + S&M 5 = 54
If you've got an apprentice to help, we'll presume an additional + 6-- so 60.

If you're using Covenants and lab specializations, you could squeeze out a bit more for the space-- this is a rabbit hole of its own, so I'll just say +4 and leave the details to the reader. You could experiment, to gain a bit more, maybe + 9 on average (+3 risk & a +6 simple roll); there's a chance it all goes to hell, but this gets us to +73. If you've got a familiar with an intelligence of +3, and a MT of 6, you could get to the magic 82 target, but you'll be rolling on the risk chart.

Other options to adjust the lab total-- another helper in the lab, a MMF in something Mu/Te relevant, or-- and this is a big deal, get a laboratory text detailing the already created item. In this case, you'll just need to get past 41/61, and we can see that's feasible, even by yourself at MuTe30. The lab text could be traded from a Verditius, found in a ruined covenant's vaults, acquired in trade. Then you'd spend a season translating the text, and the next season creating the effect. This whole process could be an adventure followed by a busy Autumn and Winter for the creation. It depends on what you want to do more of. Does your wizard want to have adventures, or do you want to grind in the lab.

It's a lot for a bag of holding, but a fun exercise.


@Ben_McFarland : Thanks for the detailed calculations! :smiley:

Based on the new rules of Terram based shrinking you need only +1 magnitude for 100x100 shrinking effect.

My Bonisagus magus has MT 5+2, Muto 5 and Terram 5; he is working with 2 nearly-gauntleted apprentices in the lab (Int 4 + MT 5+2 for the older one, Int 2 + MT 4+2 for the younger). All of them have a Cyclic Magic what gives them +3 during daytime and also Inventive Genius for another +3. Because they all are magi Bonisagi it is not a problem for them working together. He also invented a special spell for helping them in the lab.

Experimenting Lab Total: 76+d10
Normal Lab Total 67
(Lab Total: Mu 5 + Te(also An,Aq,Co,He) 5 + Int 4 + MT 5+2 + Aura 1 + Cyclic Magic 3x3 + Inventive Genius 3x3 + Older Apprentice 11 + Younger One 8 + Special Spell for LAB use 3x1 + S&M 5 --- another 3x3 from Inventive Genius if experimenting)

Based on the calculation presented here the magic in this item needs a lot of discussion within my own troupe :sweat_smile:

EDIT: Lab Total calculation extended with "(also An,Aq,Co,He)"

My logic was the same :slight_smile: It is not an extra effect if the bag can shrink all kind of solid objects, but I also felt like it is to extensive. So I added +1 to surely cover all other material, non-living Forms.

Yes, it was for the improved shrinking effect. Thank you for the suggestion - it is clearer written as your worded it.

It is important to keep in mind that when making an enchantment (lesser or not), casting requisits act as requisit for the purpose of calculating Labtot.

So, I do not think the effect itself requires magnitudes increases for requisit as would a normal shrinking spell, however requisits needed to be included in the Labtot.
Of course, if your Terram is 5, any primer and one season would allow to level up any requisit to where it needs to be.


I noticed an interesting example for the effect:
Ars M* p. 154. Object of Increased Size: "...Noble elements like gold, silver, and gems, are not affected by this spell. If any part of the item resists growth, the item as a whole does not grow. Casting requisites are required for the appropriate Form for the target."

The errated calculation of the spell is (Base 4, +1 Touch, +2 Sun, +1 stone).

Based on that the spell can even change the size of metal objects for "+1 stone" modifier if they are not noble metals.

Other thing is that this spell clearly states that the level of the spell is not increased by any requirements for affecting mainly non-Terram based material.

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That is wrong. If it is Personal range than it can only affect itself and the Target cannot be anything other than Individual (ArM5, p.111). Since it wants to use Target Room, it has to have a higher Range.

EDIT: Correction, "larger than Individual" so Part would also be usable.

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I'd say that the range would be to cast the spell and reach the room that you want to affect with your hand. Then the individuals inside the room would be affected.
In this case, since its a magical object, the room its the item itself, so i'd say that it doesn't need any range to affect the individuals inside the room.


Personal: The spell only affects the casting magus or things that he is wearing or carrying. The target is thus never larger than Individual.

Room is not a valid Target for Range Personal.

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@Heaven_s_Thunder_Ham, fair interpratation.

Do you hold the same in regards to requisites for instant transportation spells?

Humm. This is both RAW and weird. Clearly the rule was written by someone who never thought a Room could be able to cast a spell.
I might be misremembering (away from my books), but I seem to recall that the aforementioned effect (Convenient Storehouse, from MoH) uses R:Personal.

Anyway, seems like a nice place for a houserule.


Regarding the size Room vs R: Pers.

p111 "... The target is thus never larger than Ind."


p 113 "... a spell with target Room ... there is no Room containing the targets, ..."

One interpretation is that items (=targets, which is different than Target, the parameter's denominator) affected by the spell inside the Room cannot be larger than Ind.
So, in the case of the Convenient Storehouse, items need to be able to fit within the chest to be able to be affected by the effect and therefore will meet this criteria.

If we replicate the effect with Terram, it would work except for large items made of precious stone or gold, where Ind. base size is much smaller than the chest itself. One way to solve it is, of course, to increase the base effect level.

Yes, there are a few ways to read "larger than" here. If "larger than" means a higher magnitude Target, then you can't use Part with Personal, even though a part of you is smaller than all of you. If "larger than" means a bigger volume, then the room is the item so Room is not bigger than the Individual here. Since the objects need to be placed in the object to be in the room, I don't see needing to worry about the size of each object affected, but that is another place we could look at "larger than."