That's what it seems to be.
With Kurumegnik's help he is able to expand his powers and go big, but without him, he could probably still form it, but I doubt he could hold it for long.
But I assume the powers we've seen so far from him, are most likely still similar to what he could do now, albeit at probably a smaller scale.
Here's hoping that Kurumegnik has another form, and that Agito just doesn't get to crush him without too much effort. That would seem kind of... cheap. Would still be kind of cool, but kind of cheap.