I believe that Loki's species was determined by Li Xue's own greed. I also have a sneaking suspicion that he's about to change his persona and abilities to match that of his namesake and trick those cultivators that appeared.
Oh... I was wondering what the heck it was, I looked it up and seems like its one of the 4 Evil Creatures of the World, Opposite lf the holy creatures (the black tortoise, Azure dragon, White Tiger, and the Vermillian Bird). but yeah like what others are saying it matches her greed.
Loki is a fitting name. Pretty much every story I've heard involving him includes getting in way over his head and then somehow avoiding the consequences of his actions.