Sephaestus is the leader of the unicorn tribe that is being subjugated in the story. I wanted to give him some special features such as an excessively long horn and purple skin that sparkles like the night sky to differentiate him from the other unicorns in the comic.
Designing his mask that the leader of the gangsters makes him wear was tricky as it had to not only showcase his personality, but also the personality of the person who gave it to him and how she sees him (as a beautiful piece of art that she keeps caged). In the end after playing around with some shapes I settled on a style that mimics the helmets of medieval knights armour to show Sephaestus' regality and honour despite his position as a captive.