My custom Guardian of Souls finally has a complete model! (the paint job is by no means done)
I decided to go with a green color scheme (backstory reasons, and so he could stand out). it is most likely not noticeable, but his skull his etched with feint green runes.
for the color scheme, I really wanted a smoke/balefire look, so I went with a spray of chaos black, and on top of that, I painted some celesta grey where the ethereal meets the armor. the flames are highlighted with ogryn camo, and an all over wash of hexwraith flame gave the celestra grey the green hue.