Creating your own army is one of the best things about 40k. It allows your imagination to run wild. As long as your opponents are happy with your army and the creation of new rules, then anything is possible. And I think I've finally found the style of painting I'm happy with.
These corpse thralls and the Necromancer they protect are part of my own made-up army - an old Terran cult, banished for practicing the forbidden dark arts of necromancy, demonology and divination.
As they still have some ancient technology, lost to the Imperium, like the warp field generators that control these corpse thralls, I'm thinking these guys are going to be hunted by pretty much everyone. I think it's going to be a good army to play and to play against.
The Necromancers and corpse thralls are just the first wave...it's gonna be zombies galore.