at the end of season one, mudeok's body became petrified after Jin Mu rang the bells right? so the leader of jinyowon asked Master Lee to bring back her daughter's body. in order to do that, naksu's soul inside mudeok's body need to overtake Jin Bu yeon. i dont know how to explain the details actually 😠you can scroll the comments to find more accurate answers
enjoyed it so much. But i can't stand FL for being such clueless old mom.