^^
Spiritual seems to be best I think, have them act like ghosts?
That is to say, highly physical on their home realm(Dream), and an immaterial presence away from there, unless they have the power to manifest themselves a physical avatar form.
Was thinking of maybe another new race of sorts, of the 'made not born' variety.
1) Take the last shreds of personality and memory from a thousand dying minds, hurl it into the Void, where they crystallize around mindless Far Realm energies and make their way back into the Dream. These entities are far more 'human' and confused than the usual Far Realm invaders, they think they are human, as their personality and mind is constructed out of actual people. No soul though. There is some internal consistency, as these fragments tend to seek out those similar to them.
2) These thought-entities roam and invade minds in Dream, where they eventually take residence in a suitable host's mind(it must have common ground with whatever memory fragments formed the entity, perhaps it was a relative, perhaps it shared a trade, or similar personality), becoming a parasitic spiritual presence.
3) As for the host, he wakes up one morning with a thousand minds inside his head and an aching void in his soul.
2b) Some of these don't find hosts, but rather sweep up the thought-detritus in Dream, adding to its form
3b) These would become more monstrous as in seeking more humanity, they become more inhuman. You don't get more human by summing a million humans.