Myrna was one of the old women at Blackwell Keep but turned out to be a traitor. She is a master of poison and, according to Obun, one of the dwarves, made very good cinnamon rolls. She is most likely not a simple mortal but a creature of some sort. The Dragonwatch Series have not yet revealed her and the other old women's race. It is possible that they are forms of Hags or Witches, or human Avatars of other creatures, altough that is unlikely.
Source[]
- Dragonwatch (Dragonwatch #1)