"Sanctum" is a general term for a place where a mage "sets" reality to her paradigm, shaping it to her will. This Background provides a safe place to experiment--a spot protected against mundane intrusions or, to a degree, Paradox. Sanctums are not Horizon Realms or Chantries. They exist in consensual reality, although they have some amount of privacy and protection. Sanctums can vary from dungeons filled with weird science contraptions to a Verbena's cottage still room, from uptown apartments filled with alchemical and academic regalia to out-of-the-way chapels frequented by believing Sleepers.
Sanctums contain many of the bulkier foci that a mage might use--cauldrons, summoning circles, alchemy gear or clone tanks. These foci serve a dual purpose: assisting the mage with her work and helping her maintain the integrity of the Sanctum. This stock of foci can be rather unusual--herbs, devices, offerings, ancestral bones, hallucinogens and special musical instruments are a few examples.
Setting up a Sanctum requires some prep time. The mage selects a suitable place, stocks it and enacts her will upon it in some fashion. Dreamspeakers may perform a spirit-summoning rite; Ecstasy Cultists might share a visionquest; a Verbena might cast protective wards, while a Choruster might pray God's blessings on the place. New mages can inherit a Sanctum from their mentors or share a communal circle. The details should be decided by the wizard and the player.
Because the mage has "set" the reality within a Sanctum to coincide with her own beliefs, magick often considered vulgar is considered coincidental in a mage's Sanctum. This allows her to roll coincidental difficulties when using magick, regardless of its "vulgarity." Paradox is likewise figured as if an effect cast in the Sanctum were coincidental. Sanctums also reduce magick difficulties if a mage takes her time, grant a temporary point of Arcane within the Sanctum, and make some helpful skills possible. These effects last indefinitely, so long as the mage periodically "re-sets" the room's paradigm. Though these benefits apply only inside the Sanctum, fighting a mage on her home ground is a dangerous task.
Many esoteric supplies can be kept or grown in a Sanctum--potions, minerals and metallic ores, animal components (raven's claws, rabbit pelts, goldfish and white mice), musty tomes, strange bubbling serums or whatever fits. The source of these components can be anything from a classic witch's garden to a junior high school science lab "gifted" by student discoveries. Mages of all types sharpen their concentration with the proper "trappings." These usually depend on the type of Sanctum.
Sanctums may only encompass a room or two--no more than 200 square feet or so. Different Traditions are at a +1 difficulty to use each other's "workspace" due to minor paradigm differences. Some mages may not use others' Sanctums at all--a Son of Ether won't have much use for an ancestral burial mound. Sanctums are rated by their stock of supplies, their effect on magick roll difficulties, and the effective dots of Arcane the owner gains when "home."
• Barely adequate stock; no reductions for difficulties, although the owner's magick is all coincidental here. One point of Arcane.
•• Small stock; difficulties reduced by 1. Two points of Arcane.
••• Average stock; difficulties -2. Three points of Arcane.
•••• Good stock; difficulties -3. Four points of Arcane.
••••• Excellent stock; difficulties -4. Five points of Arcane.