This site contains information about using the Ars Magica (ArM) magic system with the d20 System from Wizards of the Coast (most notably the system used for Dungeons and Dragons). The Ars Magica magic rules are widely hailed as the best ever created, and seeking a more flexible magic system, I took a crack at adapting them for d20. Please note that this site is focused on converting the magic rules, not the entire Mythic Europe background, campaign and flavor (although the magic system draws much from these).
It is my first humble attempt; I welcome all comments, feedback, and—in particular—ideas for improvement. Also note these rules have not yet been play-tested.
Note that to use these rules, you will need to have a copy of both the Player's Handbook, 3rd edition, and the Ars Magica core rulebook 4th edition. I have not comprehensively duplicated the rules from Ars Magica needed to use its magic system in a d20 campaign. The many detailed rules for spell level calculation, formulaic spell effects and statistics, and virtues/feats (to name a few details) are not duplicated here.
Comparisons with the D&D Wizard
First and foremost, the ArM Hermetic Mage is very powerful, and will end up dominating any campaign to which the class is added. The reasons for this is pretty simple; the Hermetic Mage was taken from a whole campaign setting, Mythic Europe, in which they are the dominating, albeit behind-the-scenes, force. Even in terms of game play, the whole experience of Ars Magica revolves around the mage, and "adventuring parties" center around one or more magi, with their companions (somewhat subordinate associates) and the lowly "grogs" playing supporting cast roles. Finally, Hermetic spells tend to be more powerful, often doing damage or having effects without the benefit of a saving throw for the target.
Here is short synopsis of how ArM magic, as adopted to d20, differs in other ways from D&D magic.
| ARM | D&D |
|---|---|
| Magi use a roll when casting spells. This roll is basically a d20 roll plus a casting bonus. It must exceed the difficulty number of the spell being attempted. | Spells automatically succeed when cast. |
| Spells designed using a point-based system that results in a difficulty number for casting that spell. | Spell design is somewhat arbitrary and subjective. |
| No need to prepare spells. They can cast any spell at any time. This is somewhat like the D&D Sorcerer class. | Wizards must prepare spells before casting. Preparation is constrained by spell level and "slots" available. |
| Can cast both learned "formulaic" spells and and spontaneous spells. Spontaneous spells are designed on the spot. | Spells must be both pre-defined and learned. No ad hoc spell design or casting. |
| Can attempt to cast any spell. Failures can have anything from no effect to extraordinarily dire consequences. | Spell casting cannot generally fail. |
| Spell casting can result in fatigue, especially for poor casting rolls. | No side effects from casting spells. |
| Magi almost always have an ability to resist magic. | Only rarely do D&D wizard have spell resistance, although it is sometimes conferred by magic items or spells. |
| Casting can be modified, ad hoc, in terms of range, duration, target, gestures, and voicing. | D&D wizards can select and use feats to modify some spell characteristics. |
Contents:
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Coming Soon:
| Rules for Piety, church "classes," and more. |
| More conversion notes for ArM spells |
| More laboratory rules |
| Certámen rules |
| Twilight |
| Guidelines for converting ArM characters |
| Conversions of other casting "classes," like hedge wizards. |
Important Links:
| Atlas Games now giving the ArM core book away for free! |
| EN World's 3rd Edition News—The heir to Eric Noah's legendary d20 System news site. |
| 3D System Reference —part of the open gaming system for d20 System. |
| Project Redcap—the definitive Ars Magica portal site. |
| Sovereign Press, in their book Codex Mysterium, describes has a magic system something like ArM for their Sovereign Stone campaign setting. |
| Mongoose Publishing, in their book Chaos Magic, allows point-based construction of spontaneous spells. |