View source for The Mysteries: Revised Edition Chapter Thirteen: Mercurian Magic

=== Mercurian Groups in the Order ===
==== The Cult of Mercury ====
== The Neo-Mercurians ==
=== Mercury ===
=== The Cult of Heroes ===
==== Neo-Mercurian Road Magic: New Ranges and Targets ====
=== Cult of Mercury and Neo-Mercurian Spell Mastery Special Abilities ===
Mercurian magicians excel in Formulaic and Ritual Magic, and have developed an extensive range of Mastery Abilities. These Mastery Abilities were originally described in [[Houses of Hermes: True Lineages]], but for convenience they are repeated here.

These Mastery Abilities can be learned by any magus who studies with another who knows the ability — if a magus has studied with a maga who knows a particular special Mastery Ability, then any time the magus earns a level in Spell Mastery, he may opt to choose that special ability instead of those in ArM5.

Most magi in the True Lineages prefer to share this specialized knowledge only with their apprentices, although their methods may be written down in books that anyone can read, and it is not impossible for a master to decide to teach a student with very similar goals and loyalties. However, most remain cult secrets, with the exception of Ceremonial Casting (detailed in [[The Mysteries: Revised Edition Chapter Four: Curious Common Magics|Chapter Four: Curious Common Magics]]).

Characters who take Mastered Spells during character creation and who have access to these abilities during appren- ticeship may spend their mastery points on them if they wish. They are known by both worshipers of the Cult of Mercury and members of the Neo-Mercurians.

==== Adaptive Casting ====
This special ability may only be taken for General spells. The magus may use his mastery score and all the special abilities associated with this spell whenever he casts the same spell at a different level.

==== Ceremonial Casting ====
The maga may use ceremonial methods when casting this spell, increasing the casting time and adding her Artes Liberales and Philosophiae to her total. This cannot be taken for Ritual spells, which always require Ceremonial Casting.

==== Disguised Casting ====
When casting this spell, the magus may suppress or alter his sigil, to hide his identity or make the spell appear to have been cast by someone else. Since this actually changes his sigil, it is impossible for others to recognize the magus from it, although magi might be able to recognize that a fake sigil is not genuine. When the caster mimics the sigil of another magus, he may add his Spell Mastery score to the roll that determines how difficult it is to recognize.

==== Lab Mastery ====
The maga understands the theory of this spell so perfectly that she may add her spell mastery score to her Lab Total when designing effects that are similar to it (see [[Ars Magica Definitive Edition, Chapter Eight: Laboratory#Similar Spells|Similar Spells]]). This is in addition to the standard similar spell bonus.

==== Learn From Mistakes ====
The first time in a session that the magus botches a roll for this spell or fails it by exactly 1 point, he gains 5 experience points toward mastery of this spell. The roll must come up naturally in the course of the story.

==== Stalwart Casting ====

This spell is less exhausting for the maga. If it is a Ritual, she loses normal Fatigue instead of long-term Fatigue when casting it, and half as many Fatigue levels, rounded up (but always at least 1). If it is formulaic, she never loses Fatigue levels because of a low casting total, even if the spell doesn’t succeed.

=== Hermetic Sacrifice — Minor Hermetic Mystery Virtue ===