I had the chance to work on this character from concept to VFX, the whole pipeline (except for most of the retopology work and final textures, done by Pol Rius - https://piranesy.artstation.com)
The final design came from iterating on the Death concept, a Titan that would summon undead skeletons as it's regular attack. I eventually started brainstorming crazy Ideas and this was the result. You can more or less track the evolution from the first concepts exposed.
As a bit of a "bonus track", I've included all my other relevant concept art tasks in the project, including some that never made it into production.
Giant Animations