[quote=@Scribe of Thoth]
What exactly does necromancy entail considering pretty much everything here is varying degrees of dead?
[/quote]

In as far as in-game engagement use would go, things like reanimating remains while on Earth (with the caveat that law-abiding folks would only be using magic to move in the vast majority of situations), control of decay both physical and not-so-physical, vitality movement, methods of detecting departed souls over a distance, and things in a similar vein to that. I don't mind using necromantic themes in spells that might not be typical necromancer fare either, as long as the themes are more than just an aesthetic thing.

For simplicity, I would have necromancy work on targets that you're expected to be engaging with unless a GM specifically says otherwise as well. 

EDIT: I'm also gonna go ahead and say that necromancy would be the way to turn for spells that initiate communication back to Decibitus without actually going back to base while on Earth via communion with spirits.