User blog comment:Omega natsu2/Episode 192: Live on for Her, Review./@comment-24053170-20140726035822/@comment-121.54.54.147-20140727122423

I still don't get it. Why would the CSK appear in front of Zeref and Mard if all was needed was the twelve keys? Remember Hisui is not even a CS mage and yet she was able to unlock the Eclipse Gate and just have to provide the go signal for the doors. It's unlikely Zeref destroyed one of the twelve keys. It's also unlikely they were invited to the CS World. If I remember correctly, Lucy was like the first if not one of the few CS mage to enter the CS world in respect of her kindess hence the CS love her so much

The only way the CSK could have met Zeref and Mard is by directly going to the human world without being summoned by a CS mage. Unless the CSK indeed allowed himself to appear during that time, then I may reconsider this theory :)