Rather, one of my players, a Terram Magus, wants to be able to construct a castle or equivalent fortification without using creo magic in an Ars Magica 5th edition game.

The rules for crafting with finesse and rego are scattered throughout at least three books. In terms of total spell levels used, what is the cheapest combination of spells that will allow a just gauntleted magi the ability to construct a castle by herself?

I'm not interested in handwaved generalities, as that can already be accomplished in the guidelines of ReTe. Instead, I'm interested in a synthesis of what all the books say about crafting as applied to magical building construction.

  • 14
    \$\begingroup\$ 1. Magically enslave populace, 2. Make them build you a castle, 3. Profit. Optional mass grave. Time tested formula. \$\endgroup\$
    – mxyzplk
    Dec 26, 2011 at 18:07
  • \$\begingroup\$ Re: Title => What about "Spanish Castle Magic" ? \$\endgroup\$
    – Nigralbus
    Mar 7, 2013 at 13:30

3 Answers 3


In 5th edition, it's fairly simple.

Rego moves matter around. This includes splitting stone (not perdo, as you're not destroying, just rearranging and moving. You're also not changing the nature of the stone, so not muto).

The following are from the Covenants book and a few other official books. Check the spell index for references.

As per crafting with rego guidelines, after you cast, you need a perception+finesse roll to emulate crafting (but at +3 normal crafting difficulty). You only need the raw materials, as the rego will hold things in place or join them or mix them, so no reagents or catalysts or bonding materials. (Unless they form part of the finished product. Then you need them to begin with and add in relevant form prereqs).

Craftsmen do get material and workshop bonuses, which make their lives easier, but magi with rego craft can do the same things much more quickly if their finesse and perception are high enough.

You only really need the following three spells, and maybe copy them for moving metal and crafting stone respectively:

Ominous Levitation of the Weighty Stone

ReTe 15

R: Voice, D: Conc, T: Ind

Move a stone through the air as fast as a bird flies.

When the caster stops concentrating, the stone immediately falls to the ground. The spell’s name suggests one of its common applications: dropping a heavy rock onto someone.

Because the stone falls naturally, such an attack is not subject to Magic Resistance. Instead, an aiming roll is required to hit the intended target (see ArM5, page 86). Attacking with this spell normally takes two rounds: one to move the stone over the target, and another to aim and release it.

Damage inflicted depends mainly on the size of the stone: +5 for a stone the size of a man’s fist, +10 for a typical building-stone, up to +21 for a large boulder (see also the Impact Table on page 181 of ArM5).

Particularly large stones can damage structures as well as creatures. The main limitation on this spell’s combat effectiveness is the availability of large stones.

Vilano himself once lamented that there was never a good rock around when he needed one!

(Base 3, +2 Voice, +1 Concentration, +1 affect stone)

The Spell of Wrought Iron (Covenants)

ReTe 15

R: Touch, D: Mom, T: Group

The spell transforms raw pig-iron from a furnace into plain bars of wrought iron, as if a blacksmith had worked the iron in his forge. The magus must succeed in a Perception + Finesse roll to work the bars and separate out the slag. The task is normally Easy (6) for a blacksmith, so the base Ease Factor is 9. Failure means the iron and inclusions do not separate; a botch means that the inclusions go unnoticed, and the iron will be flawed and crack under strain. (Base 2, +2 Metal, +1 Touch, +2 Group)

The Phantom Blacksmith (Covenants)

ReTe 20

R: Touch, D: Mom, T: Group

The magus transforms iron bars (or other ready iron) into a crafted and formed result, as if a blacksmith had worked to the magus’s instructions. The magus must succeed in a Perception + Finesse roll substituting for the smith’s Craft: Blacksmith roll, with +3 to any Ease Factor.

Failure means that the device also fails to function; a botch means it has hidden flaws.

(Base 2, +2 Metal, +1 Touch, +2 Group, +1 flexibility)

The following additions would be useful for more versatility.

The Carpenter’s Keen Eye (Covenants)

InHe 15

R: Voice, D: Mom, T: Group

The magus learns whether wood is suitable for use in carpentry, with an indication of the treatment needed (e.g.“unseasoned — season it”, or “old, brittle, and dry — discard it”). (Base 3, +2 Voice, +2 Group)

The Mystical Carpenter (Covenants)

ReHe 25

R: Touch, D: Mom, T: Group

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, substituting for a Craft: Carpenter roll, and if this fails, the results is just a mess of chopped-up wood.

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. If the magus chooses inappropriate wood (such as green, unseasoned wood), the spell still acts — as if an unwilling carpenter worked against his better judgment — but the resulting goods will undoubtedly split and warp later. The magus’s choice of wood can be improved by The Carpenter’s Keen Eye, or the advice of a real carpenter.

(Base 5, +1 Touch, +2 Group, +1 flexibility)

The Invisible Glass-worker (Covenants) ReTe 4

R: Touch, D: Mom, T: Ind

The magus may transform a piece of glass into a finished form, as if a glassworker had shaped and formed it.

The magus must succeed with a Perception + Finesse roll substituting for Craft: Glassworker against an Ease Factor at least 3 higher than the mundane Ease Factor. Failure reduces the glass to a slumped lump as if an incompetent beginner had worked on it. Note that in the thirteenth century, most glass is not particularly clear — making clear glass is an alchemical process, beyond a craft-spell. Glass often has bubbles and distortions unless a real expert works on it, with a proportionately high Ease Factor.

(Base 2, +1 Glass, +1 Touch)

These last two are great for rounding out the magus.

Start with finesse 5 and good perception, and remember you're using perception + finesse in a COMBAT attack roll, so you'll use the combat rules not spell casting damage rules, and you won't have to worry about penetration bypassing magic might.

Invisible Sling of Vilano ReTe 10

R: Touch, D: Mom, T: Ind

Hurl a stone (of a size that could be thrown with a mundane sling) at a target within range.

Unlike the standard version of Wielding the Invisible Sling (ArM5, page 155), this spell hurls the stone as a projectile.

An aiming roll is required to hit the intended target, but if it succeeds, Magic Resistance offers no protection.

The stone inflicts +5 damage on impact and has a range increment of 20 paces.

(Base 5, +1 Touch)

The Stone Palanquin (unofficial) ReTe 15

R: Touch D: Sun T: Ind

Enchants a stone, large enough to bear the caster, to carry him along at his mental direction. The stone moves with a speed, direction, and height above the ground that he decides (maximum speed as of a galloping horse, maximum height of 10 paces above the ground). The stone can only maneuver across terrain that can support it, and so cannot cross water or crevasses without sinking unless they are no more than 10 paces deep. If the caster directs the stone to maneuver rapidly, he may be forced to make a Dexterity + Agility roll or fall from the stone.

(Base 3, +1 Touch, +2 Sun, +0 Ind, +1 for enhanced effect) (Contributor: Hargifex)

These are the added Rego guidelines:

Rego Terram Guideline

When Rego Terram spells are used to throw stones, the damage inflicted is limited by the level of the spell.

Low-level spells may be able to move heavy stones, but they cannot throw them violently enough to do a lot of damage.

  • Level 5: Hurl a stone projectile with enough force to do +5 damage (range increment of 20 paces)
  • Level 10: Hurl a stone projectile with enough force to do +10 damage (rangeincrement of 20 paces)
  • Level 15: Hurl a stone projectile with enough force to do +15 damage (range increment of 20 paces)

Impact Table

Type of Impact <-> Damage

  • Falling <-> +1 per two feet*
  • Jug dropped from second floor <-> +6
  • Inside collapsing wooden house <-> +15
  • Mature tree felled onto character <-> +18
  • Inside collapsing stone building <-> +21

*Bonus is doubled for hard surfaces, halved for soft.

Rego magic can make any change a mundane craftsman can effect, even when the magus is limited by lack of tools, time, or skill.

However, Rego cannot create matter, so whatever is in the final product must be supplied as source material: to turn iron into steel a magus needs both iron and carbon; to dye cloth or leather she must have a supply of dye.

Materials that a craftsman would use and then remove from the product, are not needed for craft magic.

For example, magic can bleach skins to make parchment without the lye that a percamenarius must use.

Rego craft magic works by rearranging existing material, and requires a Finesse roll to control this rearrangement.

(Creo magic draws on the realm of Forms to produce things, which are always at least roughly right.) As a baseline, this has an Ease Factor at least 3 higher than the Ease Factor for doing the same thing by normal craft.

Failure means that the spell produces a mess rather than a useful item; a botch means that the failure is overlooked (that is, the object is seemingly normal) but will let the user down treacherously, usually when he least expects it.

For example, a botched woven cloth might not unravel until a garment made from it is worn in public; a botched parchment might accept the ink, but flake it off when left undisturbed.

Factors which might increase the Ease Factor of the Finesse roll include drastic shortening of time.

While a day’s work in an instant is “just normal magic,” a month’s or longer effort would increase the Ease Factor by +3 for a month’s work, +6 for a season’s work, or +9 for a year’s work.

If the mundane craft would use many temporary substances to process the work, consider adding +3 or more to the Ease Factor.

Rego craft as rearrangement of materials means that some functions of the mundane craftsman are outside the province of craft magic.

For instance, a butcher can kill an animal with a knife, but craft magic cannot do this, as lifeinto- death is not a rearrangement but a destruction (which falls in the realm of Perdo magic).

(Non-craft Rego could, however,, with enough Finesse, wield a knife to similar effect.) Similarly, a skilled craftsman can examine and interpret an object’s manufacture and guess at its history or function, but this is not rearrangement of materials either, it is Intellego magic.

Extending the duration of a Rego craft spell makes the spell perform the same action over and over on the same starting materials — it is almost always inappropriate.

Craft Task <-> Craft Ease Factor <-> Minimum Re Craft Ease Factor (Finesse)

  • Trivial <-> 0 <-> 3
  • Simple <-> 3 >-> 6
  • Easy <-> 6 <-> 9
  • Average <-> 9 <-> 12
  • Hard <-> 12 <-> 15
  • Very Hard <-> 15 <-> 18
  • Impressive <-> 18 <-> 21
  • Remarkable <-> 21 <-> 24
  • Almost Impossible <-> 24+ <-> 27+
  • 6
    \$\begingroup\$ +1 just for the cognitive dissonance from your first sentence "It's fairly simple" to the fact that it's an 8 page response :). \$\endgroup\$
    – wax eagle
    Mar 7, 2013 at 11:39
  • \$\begingroup\$ :-P I got carried away... So far my Criamon magus has been 1 and 2 shotting other Magi and magical creatures into unconsciousness... with modified vilano's sling. Lvl 25, +10 damage and from touch to voice. \$\endgroup\$ Mar 7, 2013 at 11:52
  • \$\begingroup\$ Also... What I meant by simple is that in crafting with rego spells, the rego and your finesse are basically the craftsmen and tools... so you just need 1 spell per craft skill... and per material, although there can be some overlap with prereqs. e.g. the carpentry spell can be learned with terram prereq if you are plannig on using metal nails instead of pegs etc. And that +3 difficulty to finesse... especially considering the lack of bonuses from materials and a decent workshop really does make it a bit tricky to make anything better than average... \$\endgroup\$ Mar 7, 2013 at 11:53

Coming at this as a GM, not bothering to look it up, based upon my knowledge of 3rd ed...

You need to be able to cut stones - perdo terram, probably about 15-25, with the possibility of a rego and/or intellego requisite.

You need to be able to move those stones - rego terram, probably about the same level.

You want to make them into a castle: difficulty 10 to 15 Stonemason skill roll.

You want to do it in less than a year? add at least 5 to the spell levels. Less than a season, +10. A day, +20.

You should not be worried about detailed spell listings in Ars Magica - you should be looking at which arts, and "about right" and letting the player define new spells in CGen or research.

Remember, tho', there are two approaches to building a castle with magic... changing the stone into the shape of a castle, and making a castle the old fashioned style without the workers. Changing the stone is prohibitively expensive in terms of vis, so...

  • 1
    \$\begingroup\$ Refrained from -1 because my question was insufficiently clear. The game has changed a lot from 3rd ed, and I'm interested more in the identification of what amount to scholarly resources as books and previous writings on this topic. But good rough structure. \$\endgroup\$ Dec 26, 2011 at 17:54

Magic in Ars is inherently non-intelligent, meaning that your steps will have to be guided by the magus. A useful approach will be to construct a set of spells which are cast one after the other to simulate the work that a crew of mundane masons and builders could do. thus the mage will still need to construct a floorplan, and know something (have a skill in) the construction of castles. If they do not have that then the spells will be higher level.

The wider approach now accepted in 5th is that a spell can mimic the skill of a craftsman, but the caster's additional Finesse check is used to determine how good/ugly/perfect it is. The materials must also be present for the effectto not require Vis to be permanent. eg. A sword can be created with regoTerram, but finesse will determine how higher quality the sword is. The Finesse check can be made far easier by making the spell harder (+3 per 5 levels I think).

The cheapest combination of spells will be determined by how the Magus breaks apart the jobs; how many small steps? Cheapest is also an odd term as a low level spell might be faster to create, but you can also do so much less with it.

As a suggestion consider spells using the Target: Part and cast these on mountains. That means you may be able to create a spell that draws out huge amount of material from a single casting.


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