Die-rolling conventions There are eight
Characteristics: Intelligence, Perception, Strength, Stamina, Presence, Communication, Dexterity and Quickness. Each one is generally rated from −5 to +5 for humans and a Characteristic of 0 is considered 'average'. To perform a typical action, one of the Characteristics is added to a relevant
Ability, and a
d10 is rolled. The total of Characteristic + Ability + die roll is compared to a target difficulty or Ease Factor; the action succeeds if the rolled total is greater than or equal to the target number. If the action is routine or trivial and nothing in particular is at stake, the roll is read as 1–10 and simply added to the total (this is called a "Simple roll"). If there is an opportunity for
exceptional success or failure, the die is read as 0–9 and is called a "Stress" roll. For Stress rolls, results of "1" and "0" have special significance. A '1' is rerolled and the result doubled (consecutive "1"s redouble the eventual "non-1", with consecutive '1's each redoubling the result again). A roll of '0' is also re-rolled (more than once in cases of especially hazardous activity) as a Botch roll. If any botch die
also comes up '0', the action has been
botched: failed in some disastrous way. Otherwise, the roll merely equals zero, and the character is assumed to have been unsuccessful at whatever they were trying to accomplish.
Magic system The centerpiece of
Ars Magica is the system of Hermetic Magic devised by Bonisagus. It consists of 15 Arts, divided into 5 Techniques and 10 Forms. This is sometimes called a "Verb/Noun" system: the Technique is the verb (what effect the magic has), and the Form is the noun (the entity, object or substance that is affected or brought forth). These 'verb-noun' combinations can be used to cast both Formulaic spells (which are recorded in texts, are learned through study and mastered through experience, and have known, fixed effects) and Spontaneous spells (which a caster improvises with no prior knowledge other than the Arts themselves, giving the potential results greater flexibility but lower potency). Every apprentice (with a few
Ex Miscellanea exceptions) is "opened" in all 15 Arts before fully joining the Order; each Art begins with a Score of 0 and a mage may usually only increase one of them during a season (see below). Each Technique is named by a first-person singular present tense
indicative Latin verb: • Creo ("
I create") brings objects and substances into existence from nothing, or makes an already-existing target a "more perfect" version of itself (e.g. healing magic, as healed bodies are nearer perfection than wounded bodies). • Intellego ("
I perceive") detects or reveals, enhances a target's natural
senses or conveys supernatural ones. • Muto ("
I transform") alters the nature of a being, object or substance, adding unnatural traits and/or removing natural ones. • Perdo ("
I destroy") decays, disintegrates or otherwise diminishes the target, making something a worse example of its kind (i.e. the opposite of
Creo). • Rego ("
I control") involves manipulation of the target in any way that does not alter its nature, e.g. direct a target's movement, put a creature to sleep, or force a tree to bear fruit out of season. This is the main Technique used in spells of protection or 'warding'. Each Form is named by a singular
accusative Latin noun: • Animal affects "all natural living things that are not plants or humans, doing to animals what
Mentem and
Corpus spells do to people" as well as "things made with animal products" such as leather, wool, cheese, silk, etc. Since bacteria were unknown in medieval times, illness (e.g.) was considered either a form of
possession or an imbalance of '
bodily humors'; thus, magic dealing with disease is relegated variously to
Creo,
Mentem and/or
Vim effects. • Auram affects lightning, wind and gaseous substances; other weather effects typically require an
Aquam requisite (see below). • Aquam is used for any liquid, with the exception of blood (which requires
Animal or
Corpus magic to affect); non-liquid forms of water will involve requisites (see below). • Corpus (the incorrect declension
Corporem was used in older editions) applies to the human body, making it crucial to longevity formulas. • Herbam primarily involves plants, but applies equally to any organic matter, living or dead, that is not of animal origin. • Ignem involves light and heat, and is heavily represented in the fire spells of House Flambeau. • Imaginem (previously
Imagonem) deals with images, sounds, and other sensory stimuli (thus is involved in most illusionary effects). • Mentem deals with emotions, memories, thoughts and spirits. • Terram involves earth and minerals: mere soil is the simplest target, while stone, metal and gems require progressively greater investment of spell levels to achieve the same effect. • Vim ("power") involves magic itself, as well as demons (the overlap is not widely understood, but the fact that there is one is a significant obstacle to the Order's 'public relations', particularly concerning the
Church). A mage's skill when casting a spell is the sum of their scores in the appropriate technique and form. Some spells involve more than one Technique, and/or more than one Form at once; each Art used in addition to the basic pair is called a
requisite. All relevant Art Scores are compared: the caster's lowest Technique and lowest Form are used, reflecting the limiting of the caster's magical knowledge. Regardless of how high one's Art Scores may rise, there are outer boundaries to the application of Hermetic Magic (whether Formulaic, Spontaneous or even Ritual). Bonisagus's theory outlines a set of inherent Limits, similar in concept to the
laws of physics; the two central, 'Greater' Limits are: • Magic cannot influence a pure manifestation of the Divine; while earthly Relics (however sacred) and agents of the Divine (anything "separate from the mind of God") may be resistant to magic they are not immune, but it is impossible to (e.g.) interfere with a Miracle (which may be prayed for by an agent or supplicant, but is itself a direct intervention by Divine will). • Magic cannot permanently change a target's
Essential Nature (the implications of which vary depending on the target in question). There are also eleven 'Lesser Limits' (addressing more specific 'blind spots' such as aging, creation, time and the
soul) which are generally thought either to derive from the two Greater Limits, or to be flaws in Hermetic Theory which may eventually be 'corrected'. Additional statistics for every spell (which have been redefined in nearly every new edition of the game) are Target (what or whom the spell is directed at), Range (how far the Target may be from the caster), and Duration. For reasons of
balance, some spells require the expenditure of "vis" – magical essence in physical form – which all magi and covenants tend to make a point of hoarding and/or trading. No
Creo effect, for example, can be permanent unless vis is consumed during the casting. Some Formulaic Magic is so effective that it can
only be achieved with vis and an elaborate, time-consuming ritual (hence, Ritual Spells). This automatically applies to any spell of a greater Level than 50, any spell with a Duration of 'Year', and any non-Imaginem spell with a range of 'Sight'.
Character development All characters (magi, companions and grogs alike) improve their Abilities by applying
experience which can be earned through
Exposure,
Practice,
Training or
Study. Magic, however, is stressed as a multifaceted discipline with a greater variety of avenues for improvement. Magi are expected to spend months at a time with books and/or laboratory equipment: inventing new spells (or learning or modifying existing ones), strengthening their Arts, enchanting items, and so forth.
Ars Magica includes rules for magical research within the game's standard 'advancement' timescale of 3-month seasons. These seasonal activities generally concern either study of a text or laboratory activity. Although participating in adventures, missions and other endeavors outside of seasonal activity gives characters
Story Experience, the most substantial progress (and the ''raison d'etre
of many in the Order) is nearly always from the seasonal activities of magi. Hence, time in an Ars Magica'' campaign may pass much faster than in other RPGs (if, for example, all player-characters are engaged in seasonal activity, standard "roleplaying sessions" are unnecessary for that period) but is also more 'accounted for' (since regular and exact periods of activity give highly defined benefits). To accommodate this, many magi prolong their lives with unique (to each individual) longevity formulas (generally called "longevity potions", though the form one takes is not always a potion); this only
delays the aging process, however; beyond a certain point one's longevity formula will have no effect at all and must be reformulated (preferably with increased knowledge of the appropriate Arts and/or greater quantities of
vis). The increased longevity has led to a prevalent attitude among members of the Order that Companions in general (and Grogs almost invariably) will come and go – perhaps killed in action, occasionally living long enough to retire – while the Magi carry on. Magi
may concoct longevity formulas for non-magi, but this is a rare consideration, less effective than devising one's own personal formula, and is an expensive prospect in time and resources in any case. Study is primarily achieved with texts, each designed to enhance an Ability, Art or specific Spell(s). A respectable covenant inevitably requires either a respectable library or sufficient commodities to exchange for the use of other libraries, since the dominant form of Hermetic Magic is a scholarly pursuit. Magi who are able to write useful books or teach well can use these as commodities, trading with other magi for books or training (though the Code of Hermes places limits on what its members may sell to 'mundanes'). Lab Projects concern projects to enhance one's repertoire of spells or magical artifacts. All projects have a level of effect to which the character compares their 'Lab Total': Intelligence + Magic Theory ability + sum of a Form and Technique + other bonuses (which may be from local Aura, quality and specialization of lab, assistants, special knowledge, sympathetic connections from items, and in some circumstances an additional Ability). Some merely require a Lab Total to match the Level of Effect; more extensive endeavors simply add up each Lab Total in 'points' until twice the Level of Effect are accumulated. The following Lab Projects are the most commonly pursued: •
Invent Spells. The magus invents a new magical effect from scratch. A variation of a known spell is easier to invent than a completely original one. •
Enchant Device. The magus may create a magical artifact which may hold a magical effect like those of Spells. These can be used by even nonmagical individuals. Usually they cost
vis to make, but the Lab Total gets a bonus based on the sympathetic Shape & Material bonus of the material used; e.g. if one is enchanting a staff, the fact that it is a staff gives a bonus when the chosen effect is 'controlling things at a distance'. They can be made as Charged Devices (which cost no
vis but have a limited number of uses), Lesser Devices (which may only hold one effect, and must have a Level of Effect that the Lab Total can reach in a single season), or Invested Devices (which require additional preparation in advance and thus must be enchanted over several seasons, and may hold several effects based on size and material). •
Enchant Talisman. A Talisman is a personalized form of Invested Device with many additional features. Talismans have a much higher capacity for effects with which they may be enchanted, and are easier to enchant. However, should a Talisman fall into the wrong hands, it leaves the magus very vulnerable. •
Longevity Ritual. A Creo Corpus effect that prolongs the magus' life by granting a bonus for Aging Rolls, making it more likely to avoid the deterioration of age which typically begins after 35 years. Thus may a magus live two centuries or longer, barring other mishaps. Magi often pay specialists to devise this ritual for them, to get a better effect than they can personally achieve. •
Bond with Familiar. The magus may form a powerful mystical connection with another creature. Usually this will be an animal which is thematically attuned to the magus' personality and/or specialty: an Auram magus might bond with a bird, or a Herbam magus with a squirrel. The Bonding process is long and hard, but may very well be worth the effort. The animal learns to communicate with the owner, and while it does not become intelligent
per se, it is almost always brighter than a normal animal of its type. One major benefit of the bond is that the Familiar can be invested with many enchantments (with restrictions as to target and activation), but the primary, unique benefits are from the Bond Scores: the
Gold Cord concerns magic, and helps the magus avoid magical botches; the
Silver Cord concerns the mind, helps keep the magus focused and if strong enough may permit speech and telepathy between the two; and the
Bronze Cord concerns the body, making the magus more enduring and tough. ==Publications==