Building with Rego

Hi All,
I tried to figure out a versatile grimoire for building stuff like town houses, walls, castles, towers w/ Rego magic. I would like to receive some feedback and ideas to properly design and fine tune the following spells. Please note that my magus knew ReVi spells for elongate the duration of spell, that's why I use Moemntary or Diameter as Duration. I tried to crunch the numbers in HoH:S Craft Magic, HP:Shipwrigth and Great Tower, Covenants and C&G. Thanks for any insights!

For Foundation:
Earth as mud lvl 15 - Base 3 change stone/dirt into mud, +1 T, +1 Diam., +1 Part, +1 Size - The spell can change the hardness of 10 m3 stone or 100 m3 earth to be as soft as mud. The effect can be used to soften the terrain as long as stone columns can be sunk into the building site as support columns for foundation. 10 m3 of changed stone is equal of a 5 paces (meters) deep cylinder shaped mudpit with half a pace (50 cm) in diameter.

For Materials:
Metal and Stone, I Give You New Form! lvl25 Re Te - Base 3, +1 Touch, +2 for flexibility of shape and material, +1 for excessive details, +2 Group(or +1 Part and +1 Size? ) - The spell can shape 10 m3 of stone, mortar or 1 m3 of metal. Given a block of stone, bars of metal or a Part of a mountain, this enchantment with Rego craft magic shapes and cuts the materials to create the correctly formed metal items, building stones, be they part of a column, a ceiling rose or a fully-formed statue. The dimensions of stone blocks or columns are determined by the caster, just as the form of metal items. A Per + Finesse stress roll is required to control this spell against an Ease Factor that increases with the complexity of the pieces. Item Ease Factor:
An even stone block, a plowshare or iron nails 9
A column drum, iron tools or a shortsword 12
A ceiling vault rib, a statue, a longsword or a lock 15
The Creo requisite is required as the spell does not simply process or rearrange components but perfectly shapes the stone in order to do its work.

The Eldritch Carpenter lvl20 Re He (Pe) - Base 4, +1 T, +2 Group, +1 flexibility of shapes - The spell can work and shape 10 m3 wood. The magus selects a pile of wood, and the spell cuts, splits, carves, and joins the wood into the desired form. Any nails needed must be supplied, but wooden dowels can be formed from the supplied wood. The magus must make a Perception + Finesse roll to determine the success of the process. The Ease Factor is at least 3 higher than a carpenter’s Craft roll would require, so the simplest basic items have an Ease Factor of 6, increasing as the task gets harder. EF vs 9+ (as daily work of a semi-skilled craftman) is to provide good quality timber.

For Placement:
The Unseen Spirits of Stone and Wood lvl20 Re Te (He) - Base 3, +1 T, +1 Conc, +2 Group, +1 for Herbam materials - The spell can move and control 10 m3 of stone, mortar or wood, or 1 m3 of metal. The caster can move the stone, wood or metal parts of a building to their places, join them as required. EF vs 9+ (as daily work of a semi-skilled) for building a 10 m3 part of a wall. EF vs 12+ if the section has any special feature like archs or delicately shaped windows. EF vs 15+ for an instant stone-walled town house or precisely form the stone archs of ceiling which supports the next level of the building.

For Quality Control:
Feel the Heartbeat of the Monument lvl25 In Te (He) - Base 4, +1 T, M, +3 Structure, +1 excessive information - The caster can sense every detail about the stability and structural integrity of the target building. You know what is the weakest point in a building, how and where it needs to be strengthened. You know the "force lines" where the structure wants to be closer to the center of Earth and you know how to fix the structural problems of the building.

Separate the Poor Wood lvl10 In He - Base 3, +1 T, M +2 Group, - The caster gains a general knowledge about a pile of wood being touched. It can be determined which one is good for carpentry and which one is unsuitable for building purpose.


First of all, it has long been debated whether the "Sustain a spell" ReVi guidelines can lengthen a Duration or simply keep Concentration up for the caster. In my troupe, we assume it's the latter. YMMV.

Second "Metal and Stone, I give you new form!". I would remove the Creo requisite to "perfectly shape the stone". I would allow the spell to only work on metal, or on stone: as it stands it feels too general compared to existing spells, and it's not something that I'd allow a magus to bypass simply by adding magnitudes (so, I'd add +1 magnitude for flexibility, and that's it). Finally, just to be clear, no reshaping of stone except by "carving" i.e. you can't transform a block of stone into another shape of the same volume (but with metal it's ok).

Third, "The Unseen Spirits of Stone and Wood", that's ok as long as "joining" is not what a mundane craftman would consider unnatural (e.g. melding stone seamlessly), but I have not checked the Ease Factors, and I suspect they are slightly off. There's one crucial aspect to it though. What you make with craft magic is a fine specimen of its type, if the Finesse roll succeeds, and you start with the right ingredients. Without proper mundane knowledge, you will not know if the wood or stone you are using is "good" for the building you are creating. Similarly, and perhaps more importantly, while you can build a whole house from scratch just with Finesse, you cannot build it one wall at a time -- or add a floor to it without "rebuilding it" from scratch, unless you are a sufficiently competent mundane craftsman to know that it's a wall of that thickness and weight etc. that you need for the house.

Fourth, "Feel the Heartbeat of the Monument", I would remove the +1 magnitude, but I would definitely not allow the "you know how to fix the structural problems of the building" part. That requires a framework of mundane understanding that a spell cannot provide. Compare with InCo10 "Revealed Flaws of Mortal Flesh" that identifies correctly what ails the target, but not how to cure him.

Fifth, "Separate the Poor Wood", note that while it's definitely possible to check if wood has some desired property, you need to know what you are looking for first. The spell will not allow you to understand if a particular piece of timber is large or flexible enough for a construction project you have in mind -- unless you already know how flexible is flexible enough. Again, you need a framework of mundane knowledge to turn what magic tells you into something actionable.


Thanks for the useful insight! All in all you recommend an Ability Craft:Mason or Profession:Architect to know how to fix structural problems and knowing about proper woodware, right?

keep in mind the finesse requirements for craft magic are generally going to be your greatest limitation, and a good reason to break massive construction spells down into parts.

One thing that has never been addressed which (IMO) should be is whether the finesse requirement for craft magic with target group should be based on the finesse requirement to shape one copy, or the entire lot, since how long this will take a craftsperson would vary considerably, thus impacting the finesse total required.

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If you look at HoH:Societates for the finesse rules, they technically replace crafts, they just have a higher difficulty rolls to do so. It's kinda your call whether or not you need the Mason or Architect abilities.


Yeah, the Finesse can be immense. That is why I try to use more smaller spells to manage the Ease Factor. A spell doing a daily work of a craftsman cast as FORMULAIC magic is more than 7000 workdays work in a single day with manageable Finesse Ease Factor. But I am not sure wheather my Ease Factor calculation is correct.

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This is the best route. A mason can square off several stone blocks a day, so a craft magus can crank out dressed stone blocks at a furious pace, probably faster than a gang of masons can install them.

Maybe? Sourcing materials might be the bigger issue, though this can be managed with even more magic - magic to quarry stone, magic to transport stone, etcetera.

It's helpful to have these skills to avoid craft magic penalties (HoH:Societas), but you don't need to go deep into them. I'd have a professional design the building regardless, however.

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IIRC a spell with this exact property already exists in canon. Specifically in the craft magic examples from Covenants

Well, the closest I can find is "The carpenter's keen eye", that tells you a) if the wood is suitable for generic use in carpentry and b) if it is not, "an indication of the treatment needed" (the examples of the latter being 1. unseasoned wood that needs seasoning and 2. just bad wood that needs discarding).

Note that this is very different from a spell that tells you if some wood is suitable for a specific construction project -- e.g. if it will work as the support beam of a roof -- without the caster understanding on his own what kind of wood would be needed for that project.

In other words, if you have sufficient experience in construction to know that the "right" wood for a beam is one with a rigidity of X, then InHe can confirm that a piece of wood has the desidered rigidity. But if you don't even know what rigidity is or that it's crucial for choosing the right beam, you do not have enough knowledge to interpret the answer provided by the spell (or even just to ask it): you can't ask "is this wood good as a beam?".

Here is the spell in question as presented in the OP

I have a hard time seeing where in this description you get the idea that the OP intends for this spell to work in the way you describe, i.e. to give specific details on how individual pieces of wood would perform in specific building situations. I would go so far as to say that the wording of the spell here (probably deliberately) uses almost the exact same wording as the carpenters keen eye and we should assume that it uses the same guideline and has the same results.

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Possibly from the fact that something like that idea transpired from other spells the OP posted.
Anyway, I think this is not controversial: if the notion of "good" or "bad" wood depends on the specific use, in a way that could only be judged by a specialist, InHe alone can't say whether it's good or bad -- the caster also needs that specialist knowledge. Do you agree?

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Can someone please reflect to the numbers I used as EFs in the first post?

Here's the often overlooked issue.

If you create a house with a single spell, yes, you only need a (high) Finesse roll. No need of Craft: Mason, Profession: Architect or whatever, though it helps a little. You are, in some sense, selecting your house from the catalog of platonic houses, and Finesse controls that.

If, on the other hand, you are building a house one wall per spell, then it's a very different story. For individual walls, as above you only need Finesse rolls (lower than those for a whole house): there's no need of Craft or Profession abilities, though they help a little.

But the crucial point is that the whole is more than the sum of its parts. Being able to build individual walls is not sufficient to build a house, you also need to understand how they "fit together". That's where an appropriate ability is strictly necessary, if you want to build the house piecemeal.

So, you face a tradeoff.

  1. You can have exceptional Finesse and strong Arts, and build houses one per spell (keeping in mind that, if you build castles rather than cottages, you might be slapped with the Ritual requirement for "impressive" feats -- troupe's decision). Then, you can ignore everything about mundane craftsmanship.
  2. You can have slightly lower Finesse and slightly weaker Arts, and build houses piecemeal -- one wall section, floor, cellar etc. at a time. Then you must have the appropriate mundane craftsmanship to design the whole and ensure that the "magical requests" you issue for the individual parts are for the correct parts.