I got the Caestus Assault ram primed and have started to base coat the areas that will require a black base. I used the Army Painter grey spray over a black primer coat. Most of the blackened areas you see on the model will be a dark red, starting with a darkened mix of mechrite red and black. I have a feeling I will have to put something a lot more interesting to look at on the tops of the booms though, as that looks like too much space to leave as a a solid colour. Norse runes and Celtic knots are strong contenders, although simple jags are also a possibility that would be within the theme.
I have also done some painting on a Nid model, but not the Hierophant. It seems I do not yet want to start a project that big as it will require an enormous commitment of time and I have other Nid models that are useable in a basic game of 40K. So I dusted off a Swarm Lord conversion I constructed about a year ago and have made significant progress on this model. The upper pair of swords look horrid right now but they will be significantly altered from their current state. The lower pair are closer to where I want them but I still intend to do a bit more work on those. Over all the model is coming along nicely, fits into my current Nid army, and has a much better flow and sense of movement than the GW offering. Once I saw the static Swarm Lord from GW, I was glad I went through the effort of making my own.