Chameleon
By sensing the subtle outlines of the wandering souls, Jason quickly understood that their concealment was because of their inherent racial trait.
All of the infiltrating beasts were chameleons, which was quite intriguing but also understandable owing to their unique trait.
However, the most important, for Jason was that he had figured out more about the Soul Monarch.
He began to doubt if the chameleons became wandering souls through normal means.
As such, they must have been turned into wandering souls by the Soul Monarch, or his subordinates.
Understanding this allowed Jason to figure more about the mindset of their current opponents because the chameleons were likely to have been nurtured just for the attack they were supposed to launch today!
This made many things more difficult, but it also showed that the Soul Monarch had planned everything that was currently happening.