White Wolf then released at least a dozen supplements for Third Edition, including the addition of Divine and Infernal mechanics, rules for shamanic magic, beginning the Tribunal series and completing the 'Four Seasons' tetralogy of stories begun by Lion Rampant.

In 1994, publishing rights for the game were sold to Wizards of the Coast,[5] who brought in Jonathan Tweet and started development on a fourth edition.

Development fell behind schedule, and on December 5, 1995, Wizards of the Coast announced they would leave the tabletop role-playing business altogether, although this turned out to be a temporary departure.

In this setting, Faeries actually do steal lost children, Demons cause disease and crop failure, Angels help the righteous, and dragons and other Magical creatures are real (though perhaps forgotten or hidden).

Companions are select skilled non-magi who help wizards conduct their affairs (as magi tend to be distanced from "mundanes" due to the effects of their magical "Gift").

A covenant is typically a 'home base' where the magi are in charge (though they may travel Mythic Europe for reasons of politics, resources, study or even leisure).

While magicians at this time were scattered, rarely social and highly distrustful of each other as a rule, two factors strongly favored mutual co-operation.

The other was Bonisagus' second breakthrough, the Parma Magica (loosely translated as "magic shield"): a highly efficient and easily taught personal ritual which could allow these disparate individuals and traditions to meet on common ground with some assurance of safety.

Each Tribunal holds a gathering of its magi once every seven years; attendance is not mandatory, though it is essential for certain procedures (e.g. those who have completed their apprenticeships are formally presented for official membership; the Quæsitores judge the types of disputes deemed beyond simple inter- or intra-covenant resolution).

As with any system of borders not contingent on clear demarcation such as a river or wall, the territory of each Tribunal is rarely defined with precision; this is partially illustrated (via the Fifth Edition Covenants book) with the 'Tribunal Border' characteristic, which situates a covenant in a location that could place it in more than one Tribunal (depending on political favors, conflicts over resources, and so on).

Such ambiguity can exist even with "clear" borders such as rivers or mountain ranges, since incorporating supernatural aid or power into the structure (and perhaps the constituency or lifestyle of its inhabitants) can allow them to thrive even in the middle of either such feature.

The overarching premise of the Ars Magica setting is that the "mundane" world of ordinary, physical existence is a place where four great supernatural forces have varying degrees of influence and presence.

Reason proved an unwelcome addition to the game; neither Fourth nor Fifth Edition have included this 'Realm', and all references to it have been stricken from the canonical setting.

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).

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.

All characters (magi, companions and grogs alike) improve their Abilities by applying experience which can be earned through Exposure, Practice, Training or Study.

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.

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.

Its attempts to integrate this magic into a historical context are persuasive, and the game master notes and staging tips are wonderfully perceptive."

Although Rolston gave good marks for the game mechanics, character creation system and combat rules, he was especially drawn to the magic, which he said "has elegant tone and atmosphere."

He concluded with strong recommendation: "The Ars Magica game features an original and exciting game system, a coherent and satisfying treatment of magic, a convenient and imaginative exploitation of a historical medieval setting, and an explicit and appealing presentation of a role-playing style that emphasizes the common development of the setting, narrative, and PC-group activity over the personal expression of the individual PC.

He also admired the game mechanics based around single rolls of a ten-sided die, although he found the rules added some unnecessary complications.

He concluded by giving the second edition an excellent rating of 9 out of 10, saying, "it's worth buying for the ideas and the imaginative vision of its authors, even if you don't plan to play it.

"[19] Stewart Wieck reviewed the revised edition of Ars Magica in White Wolf #19 (Feb./March, 1990), rating it a 5 out of 5 and stated that "The only other fantasy game which so thoroughly takes advantage of the art of role-playing is Pendragon by Chaosium.

"[22] In a 1996 reader poll conducted by Arcane magazine to determine the 50 most popular roleplaying games of all time, Ars Magica was ranked 19th.

A first success for Jonathan Tweet and Mark Rein-Hagen, who both went on to even bigger things, Ars Magica includes one of the most flexible, highly-regarded magic systems in the roleplaying hobby.