fantasykiller

I actually wasn't sure how to answer your question so I started skimming through his canon. I always viewed the Dragons/Invisible Thing as an entity, but apparently they were described as a 'great swirl of power' in their second canon appearance (third going by in-universe timeline). Here's a quote from the book.

The great swirl of power compressing toward that boy’s shoulder felt so threatening that it seemed to suck the color out of everything Fiamma had obtained.

(Something invisible…)

Fiamma of the Right looked back at the boy’s face.

He was still hanging his head down so his expression could not be seen.

It seemed that not just Imagine Breaker resided in that boy’s body. Just the ability to negate supernatural powers was not enough to shake Fiamma’s heart that greatly and to put him on his guard to that extent. Even then, he felt a painful illusion on his skin. He felt a deeply resounding shock in the bottom of his gut like large fireworks were going off nearby. That shock was similar to an invisible wall.

(Something is there!!)