Ej'Derha (Eege-deer-hah )is the Last Vox, the most powerful of them all. He is older than time itself and very wise. He lives a life of solitude, deep in a cavern filled with the strongest monsters in existence. Despite his solitude, he is the king of the Vox, and watches over them from on High. Only the most well trained Summoners dare to enter... not only do Summoners have to fight all the monsters that are crawling in his cave, they then have to battle him. There is a weakness he has, a special Vox one Catt has known all along...

Summoners aren't typically expected to challenge Vox on their own, nor are they always supposed to engage in combat with Vox. Ej'Derha expects a fight as he wants to know he's going to a well trained Master with proper allies, but for instance Ciel plays Hide-n-Seek with Catt in a forest. Ciel being a Vox of Kindness (a healer), he wouldn't hold up in a fight, but Ej'Derha is an all-powerful damage dealer, so naturally, fighting is his calling.

The glow indicates he has been Summoned. It's always this cyan/aquamarine color.