Nilaz, I imagine, is a very knowledgeable way to call it. Most people call it 'The void'. and I recall some people using the void in some sentences. 'Sent him to the void' or something like that, I forget exactly.
Also, hades is not hell, it is just a place for 'shadows' of people to go to, no? So a non hell place like Drov can exist very easily.