This lead me to a realisation that there are considerably more Spell Mastery abilities than mentioned in the main 5thEd book (supposedly introduced by Flambeau the Founder).
Which leads me to wonder how easy is it to create a new Spell Mastery ability? And teach it to the rest of the Order?
Presumably a new Spell Mastery ability requires a modification to Hermetic Theory, so some sort of Minor Breakthrough? And to teach other Magi, perhaps merely write a Tractatus on Magic Theory and how the new ability fits in (what sort of minimum level?).
So what sort of new Spell Mastery abilities have been developed in other people's sagas?
I have been trying to wrack my brains for such a new ability, and would mind a critique of the following:
Mastered Spell ability: Expanded Focus
A spell Mastered with this ability gains the benefit of the mage's Magical Focus, so long as the following conditions are met:
the mastered spell must belong to a Techinque/Form combination that the Mage's Magical Focus already affects.
The spell must already be mastered to as many levels as the magnitude of the spell - the more powerful and intricate a spell, the more mastered understanding of its nature is required to force it to fall under the Magical Focus.
The mage's casting sigil for this mastered spell now includes a noticeable identification of their Magical Focus. (Assuming the Magical Focus didn't normally appear in the Casting Sigil).
I keep thinking this might be invented by a Tremere mage who wants to make their magical focus in Certamen practically applicable.
Look at HoH:TL p.29 Breakthroughs in Play: a Tractatus about Spell Mastery for a specific spell should be enough to communicate a new Mastery Special Ability. Of course, Mastery Special Abilities can break sagas at least as easily as other Breakthroughs and require the same troupe discussion and approval.
In one campaign I was in, I had a Mastery ability that allowed me to reduce the Vis cost for a Ritual spell by my Mastery level, to no less than half the original value. But we were in a low vis saga where this sort of thing was necessary. Your saga may vary.
Intensity Mastery
You can only take this mastery abilty for General spells. You can cast the mastered spell at a lower magnitude than you know it, up to one magnitude lower per mastery level, although fourth magnitude remains the minimum for Rituals. This allows the caster to reduce raw power so as to increase penetration and/or save vis.
I generally dislike thread necromancy, but I think it's ok for "collection-of-ideas" threads, which are more of a resource one can always look up than a discussion.
@ezzelino Don't worry, with how slow the forum moves this thread is definitely not a necro. I like your mastery ability and could see someone in my game attempting to create it or something like it.
Light of Andorra has a massive amount of Spell Mastery options to pick and choose from, including listing out all the cannon ones with minor clarifications on ones where it was helpful. My group raided it for our game, though we tweaked and added a few more.
Here are a few from my group that are unique or variations. Note that we have a HR/Clarification that Mastered rituals can be cast with a standard die if desired in certain situations (no external stress, no hasty casting, within an aligned Aura).
(Realm) Attunement
You are adept at casting the Mastered Spell in a Foreign Aura (Divine or Infernal; for Faerie Auras see Faerie Attunement). Reduce the penalty to casting roll and additional botch dice in the Foreign Aura by Mastery Score, to no lower than 0. This Mastery only applies to one Foreign Aura type chosen when taken, though a second selection allows it to apply to both.
(Rare, Demon Hunters [Infernal], House Bonisagus, House Jerbiton [Divine])
Adaptive Casting (Clarification)
True Lineages, p.99
This Mastery can only be taken on the highest Mastery Ability for a given spell. Once taken, consolidate the XP of any other Spell Mastery for the spell into one Ability. Excess Spell Mastery abilities must be dropped, though all the ones in the skill that Adaptive Casting was learned on must be retained.
Note: Books on Spell Mastery are not listed with level. A book on Spell Mastery of a general spell can be applied to any level of that spell.
(Common, Cult of Mercury)
Connection Mastery
For spells that target a location by Arcane Connection, you have developed innate Arcane Connections that can be used as the target of the Mastered Spell. You may attune one location per point of Mastery. Additionally one attuned location can be changed each time your Spell Mastery increases, allowing you to change your old bond locations. (Normally used with teleport spells)
(Rare, House Bonisagus)
Hastened Ritual (alternate to Light of Andorra version)
This Mastery allows the hastened casting of Ritual spells, reducing the time required to cast it. Subtract your Mastery score from the minutes per magnitude (base of 15) that it would normally take. This Mastery can be combined with a Casting Space, though the fastest is casting speed is 1 minute per magnitude. Any ritual cast faster than normal is considered under stress and can botch.
(Rare, Cult of Mercury)
Ward Mastery
You are adapt at finessing the maxim out of your wards, increasing its effect level and penetration by your Mastery Score. The bonus is to the effect level of the spell, not the actual level (it does not become a ritual if taken past level 50 by this effect). This Mastery cannot be used with AotH.
(Rare, House Bonisagus)