Rex Igneous is a colossal and muscular Earth Dragon of unknown kind who towers over ordinary dragons and is at least eight times the size of a human. His brown skin is partially equipped with dark brown, jagged rock armor around his head and shoulders, his spine, as well as his chest area. Golden gems shine through this at selective spots, including the tips of his wings, which appear to glow occasionally. Two sharp, golden-tipped horns point forward from the sides of his head.