I forgot to mention above that each costume design contains a torc, a rigid metal band that would be worn around the neck, something Cernunnos is often depicted wearing or holding.
The final image I see in my head of this character is them lounging on a living, walking palanquin made of twisted wood entangled around chunks of stone and soil. They are almost not paying attention, lazily pointing towards the viewer, commanding a horde of beasts to attack.
Here's a quick sketch of what one "leg" of the palanquin may look like.
Cernunnos is often depicted with bulls, rats and horned serpents, so I would like the extreme foreground to have a striking snake with horns. The rest of the composition will contain other animals in the act of charging towards the viewer.
I'm also toying with the idea of having the animals be made of branches and stone as well to better represent the earth element, what do you think?