That looks really good. Can't wait to see it colored. I like how there are some similarities to Brawl's and Starscreams's designs. His hands look a little odd at first, but they look like they're balled up into fists, which does look good. Keep up the good work.
Looks pretty cool. The line art is a bit light, it's a little hard to make out all the detail. Also rotating the image wouldn't hurt.