I had the pleasure of working on the character model of Mourn for Predecessor.
Proxy mesh by Yogi Patel:
https://www.artstation.com/mryogesh123
I took it forward from its proxy mesh stage to final, with further adjustments made by Art Director Rayph Beisner (Thunderbrush) cutting the staff and replacing his hand with a large "root tentacle";
https://www.artstation.com/thunderbrush
Technical animators requested the chest plates slide over each other to support the full range of motion of the shoulders and minimise clipping. Unfortunately this feature didn't end up making it into the final rig but I'm happy to showcase my problem-solving here for posterity.
Mourn concept by Igor Shapochkin