The Assistance of Legion-1.

A domain is not much different from a nascent world. They both have the same abilities which depend on the power of the soul, except that a world is an evolution of a domain that creates an isolated and enveloped space where the rules can be changed. The rules can only be changed, with emphasis on "can", it doesn't mean they will be changed. Soverick's nascent world grants him that possibility of change while Legion-1's domain grants him the certainty of it. The soul of a full-blown Origin god is no joke.

The high-rank demons are not panicking because they are all enveloped in darkness. They can't see anything, feel anything, or move anything. So how could they panic? They are trapped in an evolved and more powerful form of his cloud of darkness. 

It is only the divine sense of the demon lord that can do something and the only thing it can do is think. All that power that she is so proud of and the only thing she can do is remain capable of thought.