Board Thread:Questions and Answers/@comment-38665804-20190515140404

Pretty much every power on the wiki has a Valkyrie Crusade character in the users list, but what actually is it and why are they so OP? It's like Valkyrie Crusade is the most OP fictional verse or something, they have a character in every omnipotent power, but I've looked it up and it seems to be some kind of online card game or something. Can someone explain what they are? 