Here is the final concept of Ivy's environment.
Inspired by the various artist's work I've been admiring, I tried to focus mainly on the atmosphere and mood of the piece rather than the technical detailing. I used quite loose brushstrokes to give more of an impressionistic feel to the structures an make the overall image seem magical and mystical. I also made the lighting particularly dark to create a contrast that draws attention to the centre of the image, to the bright crystals and the skull.
edit: made it a bit more "glowy" and bright:
my inner perfectionist is at work today...
Sadly I made a bit of a mistake whilst editing this: I'd resized a version for posting it on here, and without my realising, that was the one I worked on... so the final image is actually quite small. This means it will probably appear pixelated on the final A3 concept sheet. (there had to be one thing that went wrong)