[Plane]

You're right, I took a second look at Thaumatology 25, didn't remember the "nobody can buy One-Spell Magery multiple times for different spells" part. This makes "One College Magery" and "Power Casting" (Magical Styles 29) a lot more distinctive I suppose.

Of course there is the tiered option to do stuff like "3 Spell Magery" -70% or "5 Spell Magery -60%", which is actually a BETTER deal than taking One Spell Magery twice if you specify this for your favorites.