The League hearth magic
Rings have a power all their own. They are worn to represent loyalty, and become powerful symbols of oaths and promises. Stealing a ring from someone can result in the oath or loyalty it represents being damaged in some way, and there are stories of rings used to inflict terrible curses not only on the original wearer, but on all those who are loyal to them. There are also stories that rings gain a power of their own, especially rings that represent a profound, magical or hidden loyalty - stories tell of rings that draw the shades of the betrayed to drive a villain mad.
Masks represent anonymity, and are extensively used in magic, but they also represent a hearth magic. The mask conceals the identity of the wearer, or allows that identity to be confused or connected with that of another individual, especially an iconic character. The use of masks is traditional, and can be seen as an evolution of the use of veils and cowls among the Highborn. Masks are also extensively used in ritual magic by many League magicians.
A similar fascination with identity revolves around the use of mirrors. Mirrors show the face that others see, but also sometimes reveal one's true face. There are stories of mirrors that reflect murderers as if they were still covered in the blood of their victims, or of mirrors that show parted lovers the location or fate of the one they are bound to. Mirrors have no identity of their own - they only show what is placed before them. Some Leaguers have adopted a practice originally from Holberg that encourages those with worries or wracked with guilt to confide their problems to their reflection - engaging in imaginary dialogues as they work through the concerns of the day. There are stories of magical mirrors that allow the reflection to take on a life of its own, to serve as advisors to those who use them or to act out the repressed desires of those reflected in them.