So there are necromancers, but also evokers, illusionists, thaumaturgists etc (or some variation of the standard magic schools)?
As far as some different types of undead, here's a few:
Vampires (Got most of this during a spin of research lookign for the Jade Court)
- They typically fall into one of a few broad categories, that the courts mostly fit. There are the monster creatures that only looks like a human being, and usually has the various levels of shapeshifting ability. There are the Undead type. There are also a lot of SE Asia myths of green skinned beings that could split/segment their bodies, send their heads off flying, and other such stuff, but sometimes that seems like the shapeshifting bits, while otehrtimes the green is rot and they are more animated dead style. And there are the Psychic/spiritual Vampires. Any of the Shapeshifting and/or Undead stuff sounds good for your Necro-Dead, while the Psychic Vampire sounds like a great Natural type; it could be a spirit drain, a possession thing, or an outright walking dead that found a way to steal life to keep ticking.
Other Undead include Patchwork types, with can be anything from franestien's monster to chimera creatures built from various animal and/or people parts.
You could have all sorts of fun with different types of based on the portion of soul preserved or the method/circumstances of their death, and moreso depending on how firm you are on the intangibility of the Natural types. So like a person that died with extreme lonliness might become a siren type that tries to drag the living down with them. Wereas the victim of a push-in robery/murder might be a poltergeist that violently tries to drive them off. And those are just intangible types; if you are willing to have physical types that are Natural instead of created, you can go even further with the twisted, monster stuff. A psychic vampire as a natural type would make sense for example. Or various forms of rage-monster, gluttany/devourer, etc. The Big 7 sins are always good fodder for that sort of thing.
If you can give me more on the flavor of the 3 goddesses, I can give you more for the divine type