1/ STORY: Let's be honest, this drama is more a romance drama rather than a fantasy action drama. It is the story of two persons who have opposite backgrounds and they form an alliance to reach their own respective goal but they start to develop feelings for each other while they are embroiled in a conspiracy.

1.1/ The conspiracy (SPOILERS):
200 years ago, the power of the sky materialized into a stone that brought the ability for humans to shift soul, switch bodies, absorb the energy of souls or even bring back the dead to life by summoning his soul back. These spells called "Alchemy of Souls" created chaos since one mage used them for the first time. The chaos was then solved by a Master who had the power to destroy the stone but did not.

200 years after, an elite assassin is chasing and killing mages who have banned the Alchemy of Soul. But among them, conspirators are using the forbidden spells for their own specific objective.

The conspiracy is not complex but it is not explained in the clearest way. It is unveiled bit by bit through different events and characters like the pieces of a puzzle which slowly unveils the picture. It is not easy to handle as many elements are important but they need to be understood and "digested" quickly. It needs attention and this was sometime prejudicial to how I enjoyed the story. Plus the conspiracy is unveiled and "resolved" slowly over 20 episodes.

1.2/ The romance:
The elite assassin is forced into soul shifting to save herself an ends up in the body of a weak girl and she looses her powers. She is taken as a maid in a family of mages where the rogue son is trying to become the most powerful mage. He takes her as his master to train him. But slowly romance starts to develop between a guy who is very focused and plain on what he wants and who he likes and a young woman former assassin who tries to do her part of the deal but slowly falls for her pupil as she navigates between the blurred lines of caring as a master and caring as a lover. Their story is really cute with emotions and good action when they need to protect each other. In the end ... they can finally live happily ever after. Nope. It's a joke. But the way the two of them slowly come together as an item was nice.

Beside this, there are some sub romances and plenty of love triangles. They are rather cute and not annoying. The side couples have cute scenes and cute stories. The love triangles are not too intense, not confusing for the leads or for the viewers. In fact, they mainly underline the background and personalities of the characters rather than they create angst or opposition or dirty rivalry.

All these romances and love triangles accounts for a huge part of the drama to the point it feels like a romance drama but it is not annoying because most characters involved are good people who are endearing and I could not throw stones at them.

2/ CHARACTERS - ACTORS:
- Jang Uk: a lout with a sad background story but he is a fun person, a good and loyal friend, He keeps his cool demeanor and manages to develop his powers but he also has to face difficult choices. I liked the character. Lee Jae Wook perfect.
- Mudeok : Naksu in the body of a maid. I liked her evolution from cold blooded assassin to smart maid doing her best to improve her pupil and fighting her own feelings. She is scheming and strong but also really fun to watch. Jung So Min nailed the role.
- Supporting leads: Yul, Dong Gu, Cho Yeon : All form a nice company of friends with their qualities and flaws. Underused at times but important in the build up of the story especially towards the end.
- Supporting characters: Park Jin, Master Lee, Maidservant Kim, Master Heo: Good hearted and caring for the leads and friends. I like their personality, actions and the funny moments they delivered.
- Other likeable characters: Crown Prince, a man of his duty and position, benevolent but can be ruthless. Heo Yoon Ok, nice niece, helpful and understanding. Joo Wol intelligence service, a good friend and helpful hand
- Annoying character: The big evil guy. His schemes are bigger than he is impressing himself. At times he looked lost and funny but overall does the job as the villain. Mama Jin weak mum who redeems herself. Papa Jin also in a different way. Jang Kang unworthy father who goes wandering around the world and comes back home not wiser. So-i, terrible person but necessary evil.

3/ OST: Very good.

4/ REWACH VALUE: 20 eps is very long and the story unfolds slowly due to many cute fun moments of humor. Rewatchable it you have time.

5/ OVERALL: Honestly I expected more action and fantasy and I was served more romance and love triangles. Still I am not disappointed. I enjoyed the story the conspiration and the romances and the characters that I found interesting and endearing and fun. Of course, it is no secret this is a part I. I thought the ending was very good with great pace to build-up the climax and deliver the intense final. It sets up perfectly the part II which will probably have a different tone. Very enjoyable drama if you take time to assimilate the details of the plot and if you like cute fun characters. 10/10.