Here's what I managed to do with the necrosurgeon and her gang.
The thralls didn't get much paint on. With the one standing on the bag, I just deepened the shadows a bit to make them stand out more. I just used GW badab black wash carefully applied to the crevices. The others got some shading done on them. I used GW rotting flesh thinned with flow aid and water mix and Vallejo glaze medium. I went over the spots that would receive more light a few times.
I also painted the first layers on the body parts sticking out from the bag for all of them. I started with VMC dark flesh followed by VMC light flesh highlights. All of the area was then washed with GW devlan mud to pull it all together. Lastly I added some thinned down GW leviathan purple wash to give them some beaten down look.
I've given more time for the necrosurgeon. I almost have all the surfaces covered right now. Still missing the details on the leather skirt and and the skull on the human torso.
For the copper / bronze parts I went with VGC charred brown base coat followed by VGC brassy brass on the raised areas leaving the deepest shadows untouched. The metal got a base coat of VMC oily steel. All of the arm was washed with GW devlan mud.
I've been wanting to try out the Vallejo verdigris glaze and this was the perfect spot for that. I mixed about a 50:50 mix of the glaze and Vallejo glaze medium with and carefully went through the arm trying to pick the spots that would receive the most oxidation and being aware of not overdoing it.
The mangled torso was painted in the same manner as the parts for the thralls. Still need to add the blood and gore to make it a fresh one ;)