Here's the steps I've managed so far, he's not quite complete, and unbased, but I'm really happy with how its going, and I'd be very willing to see him on the battlefield, all I need is an Eldar army for him to go with :D
Skipped a step here, but it was only the basing of yellow, then progressive drybrushing of Fiery Orange and then Blood Red to build up the graduation of the colour.
Mixing in about 1/3rd Chaos Black to the Blood Red.
Predominately Chaos Black with a hint of Blood Red just to soften it.
Here's a close-up of one of the weapons, I'm aiming for a bone like look, my thinking is that the weapons are wraithbone artefacts that are used by the Avatar, stored in the craftworld in the shrine of Khaine, whereas the molten body manifests itself in response to the change in the psychic gestalt of the craftworld as it prepares for war.
Here's where its at right now.
With the magnets of course I can manage both weapon options and head options.
There's still a few steps I'd like to add. I want to go back into the lowest sections of the molten parts of the body and add a yellow white to show the brightest areas (you can see the effect in the hand holding the staff), I'd like to do a little work on the black armour areas, some details here and there, and of course I need to come up with some kind of basing strategy but I don't have an idea what to do for that yet.
I wonder now how it'll hold up to the supposed new plastic avatar that is being released, will have to wait and see.
Any comments you might have I'd love to hear, and ideas for basing would be greatly appreciated.