At first, Zi Dan had no idea what kind of monster Dorian was, but when he saw that Valg phantom controlling that body in the shadows, he could only deduce it was a Valg variant.
Although the phantom looked similar to the animal silhouettes they portrayed, Zi Dan had the feeling that it required magic to defeat it. But he figured Jin would not be heartless to demand magic users when they were not the norm in his shop yet. Maybe a burst of chi could defeat him if Zi Dan was able to immobilise the humanoid?
And what he deduced nearly hit the mark.
When the Salamander King Dorian was killed, his soul and parts of his bodies were used as sacrifice pieces for the ritual to call Maeve's beloved Valgs out from the otherworldly dimension.