From what I remember there are only three female on land who can use divine powers ember, Myra and that servant of the goddess who came to land to search for ember.
But who is going to be stabbed?
So far we know that the new witch queen is seren.
I have this nagging feeling whenever I read about this new queen that was born 20 years ago, that this new queen is the daughter of evanthe and king theoron. after all she had slept with him before leaving the kingdom. . .