EDIT UPDATE WITH EDITED PICTURES!!!
What is really unique about this is I actually used a bunch of Walmart brand paints. I didn't have the paints I needed to do the skin, so the guy lent me his. Sage green mixed with a dark brown of some sort got the look I was going for, with a develan mud wash and a straight up sage green/sage green skull white blend for highlighting (drybrushing).
The Decaying areas where done by putting the same colour as the flesh tone in, then brown ink, then asurmen blue wash around the edge and golden/sunburst yellow drybrushing.
All in all he was fun to do and actually took maybe around a third of the time it took for me to do my banner for my blood angels. Large models I guess are just very forgiving that way.
Note, the very bright spot on his nose isn't actually there. That is just something weird in the photo. Sorry.