Sketching space gladiators in a battle

Couple of days ago I gave my students a task to design two characters - enemies with each other. At the moment my schedule seems to allow me to make that task with them. So I started to sketch an idea of two space gladiators.

As I didn't have a very clear vision what the characters should look like and not having done this kind of creatures that much before, I found it very hard to come up with anything nice.

When I couldn't come up with a decent composition easily, I used Illustrator to build it with simple shapes. My idea is that the other one is having a scifi-kind-of-blast-cannon to stun it's enemy and the other one is using the same tactic as a viviparous lizard - dropping its tail to bluff the enemy. And that tail being very showy, kind of like the peacock has.

After I found a decent composition I started to build up the characters and their details in Photoshop.

Only at this phase I started to fit in more gladiator props.

Looking forward to finish this... if my other projects just allow me to do it.