The Greatest Magic Ever Misspelled:
Ars Magica Fourth Edition Errata

Although we try to get everything right the first time, problems and typos have a way of slipping into everyone's publications. Ars Magica is no different. This page lists known mistakes in our Ars Magica 4th Edition publications and earlier books. This list does not include typographics errors (like misspellings) that don't impact the text meaningfully.

For errata on 5th Edition books, see the Ars Magica 5th Edition errata

Ars Magica Fourth Edition, All Printings

Page 125, Gift of the Bear's Fortitude
Delete the second sentence of the spell description, beginning "If the duration is "Year"...". Soak is not rolled in Ars Magica 4th edition, and thus cannot botch.

Page 188, Writing Summae
When calculating the time required to write or copy a summa on a Knowledge (rather than an Art), the level of the text should be multiplied by five.

Ars Magica Fourth Edition, First Printing

(You can tell what printing you have by looking at the bottom of the credits page.)

Page 15
The generic Ease Factor Chart is missing from this page.

Ease Factor Chart
Difficulty of TaskTarget Number
Very Easy3
Very Tough12
Extremely Difficult15

Pages 21-26
The various magus templates list the ability Hermes Lore, which no longer exists in the fourth edition. All instances of Hermes Lore should be replaced with Organization Lore (Order of Hermes).

Page 34
The description for the +1 Virtue Strong Writer is incorrect. It should read:

Strong Writer: You write about magic with great speed and enthusiasm. You copy spells from your shorthand at (Scribe Latin x 40) levels per season, and copy (Scribe Latin x 90) levels of spells that have already been written out per season. All summae, libri quaestionum, and tractatus you write have a +3 Quality. When writing summae, you accumulate two more levels per season than normal. You copy summae at (Scribe + Dexterity) x 4 levels per season.

Page 56
No example specialties are listed for Leadership. Possible example specialties include magi, mercenaries, bandits, armies, intimidation, and grogs.

Page 70
The fourth bulleted item in the list of things that non-ritual spells can accomplish should be deleted. (The one that begins "They cannot have a duration...").

Page 72
In first full paragraph on this page, readers are referred to "the table below." That table is actually on page 71.

Pages 91-92
The text alternately refers to a Waiting Spell and Watching Spell. These instances should be changed to Watching Ward, which is still found on page 160.

Page 109-110
The spells Beast of Outlandish Size, Growth of the Creeping Things, The Immaculate Beast, The Beast Remade, and Steed of Vengeance should have the vis-boosted duration of Permanent, rather than Instant.

Page 137
Flames of Sculpted Ice should have a Terram requisite instead of an Aquam requisite.

Page 142
Veil of Invisibility should have the range Touch/Reach rather than Reach/Touch.

Page 190
In the example under "Writing Tractatus," Ball of Abysmal Flame should be referred to as a seventh magnitude spell.

Page 207
In the second paragraph under "Repair," the figure "300 silvers" should be replaced with "10 pounds of silver."

Page 208
In the "Supplies" section, each instance of "3500 silvers" should be replaced with "500 pounds of silver."

Page 209
In the "Income" section, each instance of "350 silvers" should be replaced with "50 pounds of silver" and the instance of "325" silvers should be replaced with "25 pounds of silver."

Page 210
In the "Hermetic Books" section, the cost of summae should be clarified to read "summae cost twice the sum of Quality and level."

Page 236
Grand Tribunals occur every 33 years, rather than every 28 years.

Pages 244-245
The entire section on regiones should be replaced with the following, to make it agree with the regiones material in Faeries.


Occasionally, within very special supernatural areas, special types of auras arise. These may exist within larger domains or by themselves, and may be of any type of aura. They are called regiones (singular regio, "realm"). Unlike other auras, regiones form self-contained worlds unique to the realm that they are aligned with.

Regiones have aura ratings from 1 to 10, which affect supernatural powers just like other aura ratings. The only concrete mechanical difference is that vis use in regiones other than magical is dangerous--double the botch dice in such environments.

Regiones consist of several levels of aura, layered one on top of another in order of increasing power; the lowest level is connected to the mundane world. To picture this phenomenon, imagine the contour lines of a hill on a map. Each line, from the bottom to the top, is like an aura rating within the regio. The mundane world is like the flat land surrounding the hill. And, just as contour lines encompass smaller areas towards the top, so levels of higher aura rating tend to occupy less space than those beneath.

The aura levels of a regio occupy space, much as contour lines represent height on a map. In reality, a hill occupies three dimensions, but the map compresses it into a flat image. Likewise, each level of a regio is a different supernatural dimension, but all coexist in the same mundane location. The illustration demonstrates this pictorially.

There's nothing to distinguish regiones from other auras, until one realizes that varying levels of reality exist on the same spot. A regio level that is more attuned to its realm has a higher aura rating, and so looks different from the rest. Lower levels appear only slightly changed from the mundane world, while higher levels tend to acquire many of the characteristics of their native realms.

Regiones have inhabitants, just like other areas of supernatural aura. These beings tend to cluster on specific levels, though they can cross level boundaries freely. The higher one travels in the regio, the stranger and more supernaturally aligned its inhabitants become.

Entering and Leaving Regiones

When physically crossing the boundary of a regio, travelers disappear from the ordinary world and enter supernatural realms. There are three methods of entering regiones: being lead, voluntarily entering, and getting lost.

Any being directly connected to the realm associated with a regio can automatically lead up to a dozen mortals or magi into that regio. Faeries can lead mortals into faerie regiones, angels and people with True Faith can lead people into divine regiones, demons and people who have sold their souls can lead people into infernal regiones, and magical beasts can lead mortals into magic regiones.

Voluntarily entering regiones involves seeing the next level of the regio and then entering it. Once a level has been seen it may automatically be entered. Only characters with some sort of special perception may see into regiones. Second Sight and Magic Sensitivity both allow characters to see into magic regiones. Sense Holiness & Unholiness allows characters to see into both divine and infernal regiones. Faerie Sight (a +1 Virtue described in the Faeries supplement) allows characters to see into faerie regiones. To see a level, roll a stress die + Perception + the appropriate talent against an ease factor of 5 + (2 x the difference between the level you are on and the level you are trying to see). For example, the ease factor for trying to see from a level 4 regio into a level 1 (or vice versa) would be 5 + (2 x 3) = 11. Modifiers for local conditions or for specific dates and holidays can change the ease factor by as much as +/- 10. Carrying an object associated with the realm can subtract up to five from the ease factor.

Magi can cast level 20 InVi spells to see into regiones. A different spell must be learned for each of the four types of regiones. Many alchemists and herbalists know how to make salves and potions which allow users to temporarily see into regiones. Anyone who can enter a regio can also take along up to a dozen others with them.

Beings who become lost near a regio boundary may roll to see if they enter (or leave) accidentally, even if they cannot normally see in. The ease factor is the same, but only Perception is added to the stress roll.

Hedge Magic


With the introduction of formulae that require the summing of more than one Ability, there is the potential for multiple specialties to come into play on a single roll against a single ease factor. Storyguides may wish to consider allowing a maximum of one specialty bonus to be added into any single die roll.

Pages 37-40
Charms of the cunning-folk which increase Knowledges have the potential to become abusive. Such situations develop when a charm is made that increases the ability to create more charms. It is recommended that the creation of charms which increase Knowledges not be allowed.

The Wizard's Grimoire, Revised Edition

Table of Contents
"Excerpts from the Peripheral Code" starts on page 25.

Page 16
In Code of Hermes sidebar, replace "...nine hundred and fiftieth" with "...nine hundred and fifth"

Page 58
The Díedne Druidic Magic Virtue should give bonuses to Animál and Herbam, not Animál and Mentem. Also, delete the clause 'save that they cannot be increased'. Knacks cannot be increased anyway.

Also, delete the clause "save that they cannot be increased." Knacks cannot be increased any way.

Page 76
The Exempli Gratia is incorrect. The cost to improve should be equal to the difficulty in both cases: six pounds and nine pounds, respectively.

Page 78
Replace "(11 vs. 5)" with "(12 vs. 5)"

Pages 122-125 (new book types)
A magus can copy three commentaries (or make three copies of a single commentary) in one season. It takes one season to make a copy of an Authority.

Page 139
The Faerie spell The Proper Beast is (MuAn15).

Page 141
The Faerie spell Wind at the Face is (CrAu10).

Page 154
The spell The Carrier Pigeon (MuAn[Au,Im,Re] 25) should be (CrAn[Im,Re] 25).

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