User blog comment:B214/Question and Answers/@comment-5185939-20131005195925

Midstromgard, the Midgard Serpent is the brother of Fenrir, and both were created to help their father Loki kill the Norse gods.

We know that Fenrir has fangs that are godslayer class weapons

Does that mean Midstromgard has enough power to kill a god as well?

Also, in legends Tiamat was a dragon as powerful as gods as well. Heck, she's supposed to be the ancestor of the Babylonian gods (though that's just in myths, so in DxD who knows)

However, if she's the most powerful of the Dragon Kings, that means she'd have to be stronger than Midstromgard who 'might possibly' be capable of slaying gods.

Makes you wonder though.