I really like your concept art approach and techniques, and you've got a neat design for your robot priest character. This is just my opinion, but I'm not sure if this character design fits this contest brief. They're asking for an 'epic champion of sci-fi or fantasy" but I don't get that champion vibe from this character. He seems too humble. I don't wanna sound harsh but that's how I feel.
I don't know about that robot wing either. It feels tacked on and doesn't look like it fits any practical purpose outside of 'symbolism.' I love the detail you put into his robot body and religious clothing.
If you want, maybe rethink how his character can fit more into the contest brief aesthetically? Or maybe wait for more opinions to see if they think otherwise?