Ok, so I spent sunday afternoon trying to figure out how to incorporate a warm light into the illustration and here's what happened:
It didn't seem logical that the soldier had a sword, a shield AND a torch at the same time, so I thought why not he threw the torch and then gets ready for battle? Didnt like the look of that that much
Then why not add a second soldier that is throwing the torch? Also not a big fan, plus I felt it took away a little bit of the menacing aspects of the aztec by having a 2 vs 1 battle, it's not very Souls like 
Then I thought having the skull on the necklace on fire could work, as that sets my warm light right on the focal point of the piece, and I liked that one
But that ment I also had to update the concept art and the turnaround. Yesterday I worked on the concept art, and later today I'll be working on the turnaround to have a consistent design across all pieces. All that's left is for me to come up with a reason for that flame within the lore of my design haha
