A list of the saga's initial House Rules. More can be added later is needed and agreed upon by the troupe.
- Rounding Totals: Whenever the rules don't specify how the result of a division should be rounded, all fractions are rounded down. For example, an Affinity applied to 5 xp (thus 7.5) will be rounded down to 7 xp, while a Fatigue-less spontaneous casting total of 4.8 will be rounded down to 4.
- Sourcebooks: Starting characters must be built using only the 5th Edition core rules. That includes spells selection, although a few (1-2) spells may come from other sourcebooks, or custom-designed based on guidelines from the core book, may be allowed at the storyguide's discretion. The material presented in the Houses of Hermes trio of books (True Lineages, Societates and Mystery Cults) can be used as an inspiration for background, but the more mechanical aspects (virtues, flaws, spells, etc.) will not be used unless specifically allowed.
- Area Lore: Every character must start play with at a score of 1 in an Area Lore, representing the environment in which he lived. This may be from childhood experience, linked to the covenant where he was apprenticed, the place where he worked, etc.
- Area Lore Mutability: The knowledge of a specific area where a character lives can be slowly transformed into knowledge of a new area when he moves. For every year that a character spends in a new environment, he can transfer 5 xp from an Area Lore that he already had into another Area Lore. This has no impact on the amount of experience the character earns during the year. This is optional and at the choice of the player, but is subject to troupe approval.
- Penetration: Penetration can be negative. This does not prevent the effect from affecting a mundane creature, but any form of magic resistance will block it, even if it is 0.
- Requisites: There is no need for a requisite to cover the form of a talisman when the magus is touching it. So a magus with a sword talisman who casts Seven-League Stride does not need to include a Terram requisite to bring it along. The same is true for a familiar who is of small size (-3 or less) in its natural shape (i.e. not because of a power or spell).
- Talisman: A talisman is considered to be part of the magus when he is touching it. As a result, a shapechanging magus can transform his talisman along with himself. A magus with the Bjornaer, Shapeshifter or Skinchanger virtue can do this automatically. A magus using a spell does not need to add a requisite for the Form(s) of the talisman. However, when the talisman is transformed that way, the magus cannot use its attunements, nor activate any effect enchanted into it.
- Installing a lab: Requires having an opened Gift.
- Aegis of the Hearth: Needs to penetrate in order to prevent a creature from entering the Aegis. It still penalizes the powers of a creature able to enter it.
- Aegis of the Hearth: Does not blow down Parma Magica, or suppress an active power or spell entering it.
- Aegis of the Hearth: If the Aegis is stronger than the level of an effect from an enchanted item foreign to the Aegis, the effect fails to activate. The level of effect excludes all enchantment modifications, except for those for Penetration. So a wand enchanted with a Pilum of Fire (lvl 20), usable 12 times a day (+4 lvl) with +10 Penetration (+5 lvl) is considered to have an effect level of 25. So it would work within a level 25 Aegis, but fails to activate in a stronger Aegis.
- Writing Books: Copying books on an Art requires having an opened Gift. So only Hermetic magi and apprentices can copy books on the Arts. The same applies to Parma Magica, Finesse and Penetration. But books on Magic Theory can be written about and copied by non-Gifted individuals.