All rules changes reference the fourth edition of the Ars Magica rules.

CHARACTERS: CHARACTERISTICS (pgs. 31-32): If you don't like the numbers you rolled multiply them all by x-1. If you still don't like them throw them out. Once you have numbers you're happy with you can assign the four numbers to the four characteristc pairs as you see fit

ABILITIES: SPECIALIZATION (pg. 52): Whenever an ability increases by a level you can change your specialization. You can also add a specialization at the end of any game session.

ABILITIES: MAGIC THEORY (pg. 58): The Magic Theory Increase Table shall be used [see ~ftp/pub/ars-magica/tables/201-magictheory on soda.berkeley.edu].

MAGIC: PARMA MAGICA (pg. 73): Parmas can offer partial resistance from some penetrating spells. In addition, they slowly drop when hit by spells. Recall for the following that ( resistance = parma * 5 + form + stress die ).

Protection. If ( penetration <= resistance ) spell has no effect. If ( penetration > resistance ) but ( penetration <= 2 * resistance ) spell has half effect. If ( penetration > 2 * resistance ) spell has full effect.

Ablation. If ( penetration <= 2 * resistance ) Parma drops 1 point. Else Parma drops 2 points.

Timing. It takes 1 round to increase your Parma by 1 point or decrease it by 1 point.

Charms Against Magic. Work in all ways as Parmas.

MAGIC: MULTIPLE CASTING (pg. 75): You must have a spell mastered to multicast it. Apply a -5 to your casting roll for each additional spell you cast, above one.

LAB: SEASONS (pgs. 80-101): The basic unit of lab time is not 1 season but 13 weeks. A week break has no effect on lab work. For every day of lab work missed above 1 week, 2 penalty days of additional work are required. The same rules apply for all other manners of practice, training, etc., as described in the Storyguide section (pgs. 185-192).

LAB: BASIC LAB TOTAL (pgs. 80+): Although you may only do one type of work during a season (ie learning a spell, inventing a spell, making a magic item, etc), if you have a sufficiently high lab total, you may invent more than one spell, learn more than one spell, etc, in a season. If you do multiple things from different techniques and forms, use the lowest technique and the lowest form for your lab total.

LAB: APPRENTICES (pgs. 100-101): It is not necessary for all of your scores to be 5 to teach an apprentice. However, you must have a score of 5 to teach an apprentice any specific art, and an apprentice must be taught one new art every year.

The training of an apprentice is a time-consuming task. The apprentice is only available to work with the magus for 1 season each year, but these seasons may be "saved up", to a maximum of 3 seasons in a year (1 season of training is always required each year).

Apprentices may do no work which requires them to go off and work on their own, without the direct guidance of their magus [ie making vis, inventing some magic item on their own, etc].

SPELLS (pgs. 102-160): The levels of all spells will be doubled.

SPELLS: DURATION (pg. 104): If any spell with a non-instant duration is upon a spell caster, their spell-casting ability will be decreased by one point per rank of the spell.

STORYGUIDE: EXPERIENCE AND ADVANCEMENT (pg. 185): Each grog, covenfolk, or companion gets the equivalent of one season worth of experience per year, provided that they were present at the covenant for at least one season during that year. This may be training, practice, or even library use, as appropriate for the character. A listing of available training for the year will be prepared at the end of each December and grogs and covenfolk shall be updated at that time.

THE REALMS (pgs. 238-245): Whenever someone enters an aura in which they could not have cast a spell that they have up, that spell will go down.

THE REALMS: THE DIVINE REALM (pgs. 242-244): Divine auras will interfere with magic at a ratio of -5/point of aura rather than -1/point of aura. When a botch occurs in the divine aura, two times the aura in botch dice shall be rolled (plus the base of one, and any other appropriate additions).