This series is fantastic. Not only its a mix of everything you love in action and fantasy series, but make it BL is even better.
The chemistry between the two is amazing. The s.x scenes (mostly in their head at the beginning of the series) are not "shocking" for regular public. It's more romantic.
The story is also fantastic. Well written to the end, you can not be disappointed.
What exited me is that after watching the last episode (12), they had a preview of a second season with a new bad guy, this time related to Phaya.

The other thing I have to say is how amazing Saint Suppapong is. As an actor, who didn't have a little crush on him in the drama Why R U? But here, he's the Executive Producer for this drama with A Natthaphong as Director. Saint is not really an BL actor of producer, and you can see the "straight touch" on this drama. Even if its a BL, the element of action and sci-fi are really taken seriously, so it doesn't look kitch. The only thing I didn't like is the "cross dressing" of Tharn as a woman (he was a woman in his previous life) like we wouldn't have understood. I think that was a mistake. They could have show the link, and then tell the story in his woman form.

Other thing that suggest a second season is all the other powerful people that appeared but we don't know who they really are like the mysterious woman at the restaurant, or the man at the end of ep12. Also, we want to know more about the stories of those legendary beasts. It's not official yet, but if the show is popular, I guess a second season may be possible by 2025 or 2026...