House Rules

Variant rules and interpretations for the Virtusaga game 

 v 1.0 - Nov 12, 2007 

Many rules are detailed in supplements that may be of interest to you even if you are not otherwise interested in the supplement's content. You can find an index to generally-useful information and rules found in supplements in the The Great Apocrypha Collection


It can be daunting to advance an Ars Magica character. For some electronic aid in generating and managing characters (or covenants), you may want to turn to the Metacreator software, that handles all the mechanics of seasonal activities and so on. Note that the program's files will need to be altered to handle our house rules.

Alternatively, you may want to use what I'm using - a spreadsheet. You can download mine from here.

The specifics of magic theory sometimes come to bear in spell design. You might want to read my take on some issues of Magic Theory.

Unless mentioned otherwise, we follow the Ars Magica Fifth Edition rules. This includes all the supplements, if and when they are relevant. 

Weaker Magic

Arts are considered Abilities for purposes of XP costs - it costs 5 XP to reach level 1 and so on. This major change results in several more minor changes.

  • Maximum art scores at character generation follow the guidelines for Abilities at character generation (i.e. the maximum score is typically 5). 
  • In order to train an apprentice, you are required to have a score of 2 (15 XP) in each Art.
  • The highest Arts in the Order's history are assumed to be around 20. Accordingly, summa are of at most level 10. 
  • You may write up to half your score of tractatus in an Ability or Art (rounded up).
  • Summa quality improves by +1 per level below the maximum, for both Arts and Abilities (not +3 for Abilities as the RAW says). The bonus gained from lowering the summa's level in this manner cannot exceed the writer's (Com + 3; +6 if Good Teacher). Book build point values aren't relevant for the players as I'm managing the covenant.
[This rule drastically reduces the power of magi, especially in combination with the weak focus below. In this new power level, journeymen magi (straight out of gauntlet) are expected to be able to cast spells of level 15 to 25, the latter with some luck and difficulty. Spells of level 45 or so are typical signature powerful spells for master magi. Only archmagi are likely to be able to create and cast the Order's most powerful spells (circa level 75), and to face off the powerful supernatureal entities (circa Might 75). You're advised to acquire mystical secrets (Virtues) rather than only spells and Arts as a means to gain power, by being initiated into Mysteries, uncovering Ancient Magic, performing Original Research, or experimenting with the initiation rites of mystery cults.]

Weaker Focus

A magical focus provides a bonus equal to half the score of the lowest Art, round down. [This makes Magic Focus a useful virtue, not a must-have.]

Weaker Multiple Casting

When multiple-casting, don't cast each spell seperately. Instead, make one casting roll. You may divide the casting total between the multiple spells. 

For example, say you cast a Pilum of Fire (CrIg 15) spell and obtain a casting total of 20 (for simplicity, let's say you have 0 in the Penetration ability, too). You may divide the casting total into one spell cast with a casting total of 15 (zero penetration) and another cast with a casting total of 5 (requiring fatigue and having negative penetration).

[This severely limits the usability of multiple casting, especially against opponents with high magic resistacne. It makes multiple-casting primarily useful to cast many low-level spells at once with zero penetration, and negates it being  a compulsory combat tactic if you are to be effective.]

Faerie Magic

Replace the spell parameters allowed through Faerie Magic with the following list:

Bargain (Special): As per core ArM. 

Days (Duration): The spell lasts a set number of days and nights, determined at the spell's design, not exceeding 33. Each day or night is a Sun duration, and if it cannot apply the spell ends For example, a spell designed to last "a night" will falter immediately if cast at daytime. This duration is equivalent to the Sun duration for the purposes of spell design.

Weeks (Duration): The spell lasts a set number of weeks, determined at the spell's design, not exceeding 16. Each week lasts precisely seven days from the time of casting, ending at sunset. Casting a spell with a Weeks duration requires raw vis like a Ritual spell (but not that the spell be a Ritual). This duration is equivalent to the Moon duration for the purposes of spell design.

Year+1 (Duration): As per core ArM.

Bloodline (Target): As per core ArM.


In addition, characters with Faerie Magic may develop the Faerie Magic ability, create faerie charms, and bind faerie familiars - see Mystery Cults for details. Unlike what Houses of Hermes: Mystery Cults says, faerie familiars do not resent their binding. 

Less Penetrating Items

Adding levels to increase penetration of magic items is possible, but only increases the penetration by +1 per level increase, not +2 as the core rules say.  

Gild Training

The virtue (Gild) Trained, presented in Guardians of the Forest: The Rhine Tribunal, may be taken at character creation. However, only three gilds offer training: the Hawthorn gild, the Elder gild, and the Apple gild. (If you don't have GotF, you can gain an inkling of what these gilds are about from the Tribunal description on this site, and can contact me regarding the virtue.) 

Experience Virtues

You do gain bonus XP from having an Affinity at character generation. Multiply beginning XP in the Ability or Art by 1.5 (round down). This may allow you to surpass the usual limit on the beginning score (score before multiplication should follow the age limit).

You do not gain extra XP from other learning-boosting virtues at character generation, such as Book Learner or Secondary Insight. You may plead for exceptions.

[Any virtue can contribute to your XP, so in principle Affinity need not be accounted for specifically. But it's so easy to do so, and your innate affinity should apply regardless of how you gained the xp.]

Familiar Assistance

Familiars don't count towards the maximum number of assistants you're allowed in the lab. So, for example, a magus with no Leadership score might enjoy the assistance of his familiar and his apprentice at the same season. 


Circles & Rings

A circle needs to be drawn for effect when using the Circle target or Ring duration. The circle is broken if it is actually physically broken, which may be more or less difficult depending on the material - a metal ring won't be easy to break. Even a small break such as a hairline fracture or smudge is enough to break the circle.

However, a Circle target needs to be exposed to be effective.  If enough of the circle is covered up, the circle is still active but won't affect things beyond what's covering it. For example, if you cover a metal ring in a thin layer of dirt the ring might affect the dirt but not whoever is standing on top of it. Small disturbances, such as a leaf falling over a circle's line, can be ignored as long as the overall shape remains clear and evident.

A circle may be moved. Thus, you may for example imprison a ghost in a round mirror.

Spells of non-Momentary duration with a Circle target may apply the spell effect to either (a) all the targets present in the Circle at the time of casting who haven't left the Circle, or (b) to any target currently within the Circle. The spell can only be designed to do one of these things, not both. If the first option is used, the spell stops affecting any target that leaves the Circle and doesn't reapply if it returns. Thus, a Circle of invisibility with duration Sun may either grant invisibility for a day to a group of people waiting within it, or serve as a location where anyone that enters is rendered invisibile.

The Ring duration ends when the target moves out of it or when the ring is broken, whichever happens first. Accordingly, the target of the spell must always be contained within the ring as the spell is being cast. (Created things must be created within the ring, and the spell fails should they leave it.)

Stronger Wards

Wards do not need to surpass the creature's Magic Resistance to ward against it. They ward against creatures of Might as per the guidelines, regardless of the creature's magic resistance.

[This allows magi to ward themselves against creatures relatively easily. Actually affecting the creature may prove more difficult.] 

Automatic Area Lore

In addition to any normal XP gain, you gain 2 XP each season in (Area) Lore, typically Covenant Lore. This stops once you reach a score of 2 (15 XP).

You may always assign Exposure XP to (Area) Lore.

Wounds & Study

A wound penalty of -3 to -5 endured for a month or more reduces your advancement totals to 2/3 [not 1/2, as per ArM5 p. 179], as if you've been distracted for a month (ArM5 p. 165).

Extended Book Rules\

[We will be adopting the extended book rules from Covenants, but with a few changes, and have made some changes to the core rules as well. For ease of presentation and use, I will give a concise system and notes on further material and changes.]

A book has a Base Source Quality of the author's Communication +3 [not Com+6, as per core]. In addition, a book's Source Quality is modified by its craftsmanship, and possibly by other factors.

Superior craftsmanship is granted by professional, high quality, scribal work (+1), illumination (+1), and binding (+1), for a maximum of +3. Each requires a professional (6+ in Ability) to obtain.

In addition, books may be written using resonant materials. This provides a +1 bonus to the source quality. Any book, on any topic, may incorporate resonant materials [unlike what Covenants says]. For example, a book on Area Lore may be written on materials incorporating the area's scents. Crafting a book using resonant materials is often difficult or expensive, however, and typically requires the use of minor magics. [Further resonance as per Covenants is not possible, neither is clarification.]

A summa [and only a summa] be be glossed by its readers, if their level in the topic is at least twice the summa's and their Com higher than the author's. This provides a +1 bonus to the source quality (multiple glosses don't stack, the bonus remaining +1). 

A tractatus may be written as a commentary on a summa, which provides a +1 bonus to its quality. It can only be read with benefit by someone who has read the summa for at least a season.


A book may be copied quickly, for a x3 increase in copying speed. This denies the increase to craftsmanship through superior scribing or illumination, and furthermore imposes a -1 penalty to the quality. [This combines the core rule and craftsmanship.]

There are a number of changes to book rules in this saga, and this is a good place to note them.

A summa's level may be lowered to increase quality, but the bonus is limited to +(Com +3) [this replaces the core rule's Com+6 limit], or +(Com+6) for a Good Teacher. Whether the summa is on an Art or Ability, the increase to quality is +1 per level lowered [this replaces the core's +3 increase to quality per +1 decrease in level for Abilities].

The number of tractatus a writer may write is limited to half his score in the Ability or Art [not a fifth of his Art, as in core], round up.


 Covenants presents many more options, which you may have access to with the following caveats.

As noted, resonance may be applied to any text, not just mystical ones, but provides only a +1 bonus. Unique objects gained by adventure may have any affect on the book, decided on a case-by-case basis. Clarification isn't allowed.

Exemplars and Juvenilia are simply works that are copied quickly, as per the rule above.

Congregationals cannot be used to study from simultaneously, nor used as communal casting tablets.  They are just very large books.

Palimpsets grant the book a -3 to quality and deny both superior scribing and illumination. 

Florilegia are not allowed, nor do Folios increase the quality. 


Note that maximum Art levels are assumed to be around 20, so that maximum Art summa levels are around 10. Other Abilities typically cap out at about 10.

Magical Nourishment

 Food created magically (except by a Momentary Creo Ritual spell) does not provide nourishment. It can satiate hunger, but not provide nutrition and energy. Likewise thirst may be satiated, but deprivation of water remains a problem. The hunger (or thirst) of those subsisting on such food (or water) might be alleviated, but they still suffer all the normal  (mechanical) effects of deprivation. Intelligence rolls might be required to ascertain what's going on, subject to SG fiat.

[This rule settles an ambiguity in the RAW. The effect is that hunger and thirst cannot be overcome by magic even on a temporary basis; magi require resources (mundane or raw vis) to so much as stay alive.

Note that this does NOT extend to breathing, which can be provided temporarily by RAW formulaic spells.]

Aegis and Items

Enchanted devices with active effects entering an Aegis of the Hearth are affected much like spells cast from outside. If the activator of the item isn't part of the Aegis or an invited guest the effect's penetration is lowered by the level of the Aegis. If this brings the penetration to below zero, the effect fizzles.

Similarly, items activated inside the Aegis are affected much like spells cast inside it. If the Aegis would have suppressed the wielder's spellcasting, the effect's penetration is lowered by half the Aegis level. If this brings the penetration to below zero, the effect fizzles. Items that trigger without a wielder, including unitentional triggering, are suppressed in this manner if they weren't within the boundary when the Aegis was cast.

Supplemental Policy

I am generally inclined to accept material provided in supplements, and intend to draw on several for the saga. However, I have made some alterations and may not accept some things (especially overly complicated or unbalanced rules) so check with me. 

I intend to utilize the supplementary rules when they are relevant. This does not mean that you need to be have read the books, but it does mean that if you haven't you may be missing out on options and that I may need to stop occasionally to explain a rule-system we're using. 


I do not own City & Guild and Art & Academe, so material from these supplements won't be used. Rules that are primarily for the storyguide, such as covenant management or how a bishop's divine powers operate, will not be necessarily adopted, but this is on my end so shouldn't be bothering you.