I assume Chthon has taken many forms over the years. Through possessions and possibly his own physical incarnations. After Secret Invasion, he was freed from his imprisonment and summoned by Mordred into the body of Quicksilver. He then proceeded to do battle with a new incarnation of the Mighty Avengers. I liked this look when I first saw it, but wasn't heavily into making customs just yet. I noticed the image recently and dug out the issue to read again. I still liked the look and decided what better time than now, right? Couple different shades of red got the right look for the costume, and I knew immediately that the Adam Warlock head would be perfect. Or, the unmasked Magneto head, since they're the same. Thought Chthon's face looked very Magneto-like. I needed him to be paler than my other figures, so I dug out my old light skin tone. Worked perfectly.
