Chance of Discovery: 2
Visitors to the Library of the Forbidden will note a slight (1 point) increase to their Mastery Methods skill (if they have any to begin with), but only for the duration of their stay.
The Library of the Forbidden is a bit of a misnomer, but only a bit of one. Set up as a memorial to this Prohibited branch of magic, the Library of the Forbidden is more of a dedication to those who believed in Mastery than it is a container of knowledge. Of course, it is technically illegal to have knowledge of Mastery or to distribute said knowledge, but those who are "in the know" understand exactly how this Library works.