Here is a thread to go with the spells thread, the non-hermetic grimoire and similar threads to list new spell mastery options. following is a list of spell mastery options presently in the game which is often a pain to find.
Mastery Ability, Page, Source
Acute Sense*, 71, HoH:TL
Adaptive CastingΨ, 99, HoH:TL
Boosted Castingâ€, 99, HoH:TL
Ceremonial CastingΨ, 99, HoH:TL
Disguised CastingΨ, 99, HoH:TL
Fast Casting, 87, ARM5
Harnessed Castingâ,99-100, HoH:TL
Lab MasteryΨ, 100, HoH:TL
Learn From MistakesΨ, 100 HoH:TL,
Magic Resistance 87, ARM5,
Multiple Casting 87, ARM5
Penetration 87, ARM5
Quiet Casting 87, ARM5
Stalwart CastingΨ 100, HoH:TL
Still Casting 87, ARM5
Tethered Casting†100, HoH:TL
Imperturbable Casting 33, HOH:S
Obfuscated Casting 34, HOH:S
Precise Casting 34, HOH:S
Quick Casting 34, HOH:S
Unraveling 129, HOH:S
Rebuttal 129, HOH:S
Apotropaic Mastery 122, RoP:TI
- Quesitorial Magic (normally restricted)
Ψ Cult of Mercury (House Mercere)
†Mutante Magic (House Mercere)
This list was adapted from this original thread.