So, I have decided to paint him with White and brass armour. Not sure if this is fully factual yet unfortunately, but we know he turns into his Daemonic Primarch form enroute to Terra.
His form does change based on this interpretation of him in Horus Heresy art work. His armour is all sorts of shades above, some grey and some green, but still very different to the way he is portrayed in 40k.
His Legion (and possibly he) would have not fully changed colours to green as they are about to land on Terra for the Siege. So I hope it will come across well.
I’m quite a fan of the dire wings in this picture. I'm also heading on going for red robes (as with the Horus Heresy Death Guard colours) as I think it would be a nice contrast.