[quote=@Yankee]
Not sure how to go about the "special boon" for masters. Would this equate to just a really strong skill/spell they have, or should it be more specific? I was planning a rune user (not primordial) so would it relate to their area of magecraft or could it even be a really strong mystic code?
[/quote]

Like the others said, it's a signature of your character. Old Runes could fit, if you wish, or even a copy/reproduction of a single Primordial one, like those owned by Touko.