The first image shows some possibilities for his torso, since the ribcage didn't really give him the bulky feel. While I was at it, I decided to introduce some color scheme ideas which can definitely be expanded upon.
This next one is just me puking ideas. They are incredibly rough and I really hope play around with them more, especially with other elements such as vines, cracks, wood texture, etc. I also tried to dissect his anatomy and determined how things would fall into place. I still intend to work on his "attack points", roots, as well as attacks, which should show up really soon! As always feedback is necessary and very much appreciated! Thanks!