Dominant Ni here.
Occasionally, when I am going to write something, I have a weird sort of hunch, an elevated state, as if I feel something is trying to break out of my head; a flood applying constant pressure to the gates stand in front of it. With a snap, it comes out of my head into the text, to the external world; taking the form of a river, a sea, or a lake, depending on the context of what is created. When I start writing, I have an opinion of where my text is going to go concerning major points and the details usually fill themselves out without much thought or compulsion, as if the major points that already came to life in my imagination are giving birth to them.
I sometimes happen to have hypnagogic experiences in between sleep, which I perceive as fragments of my imagination, for sometimes I was able to put those images came in front of my eyes from my unconscious mind into behavioural patterns, thought motifs and parts that I have not discovered about myself before.