Newsarama has an interview with Mike Johnson about this issue
, it's revelations and mysteries, as well as what to expect in upcoming issues. Selected quotes from this interview are displayed below.Here is a link to a prior article here about "H'El On Earth"
Johnson: Yeah, definitely. We wanted to answer questions in the #0 issue. We really wanted it to feel like a complete story. But we also didn't want to tie everything up with a nice bow. We still wanted to leave some mystery, particularly about Argo City and the Worldkillers, which are more an extension of the events of the #0 issue and less the meat of the issue itself. The meat of the issue were the specific circumstances surrounding Kara's departure.
We've always been planning to bring the Worldkillers back, and we have some very cool ideas about how we want to do that.
Johnson: Issue #13 will be my first issue as the solo writer, and Sami Basri is coming in as the guest artist while Mahmud starts work on the crossover. But Sami's done an amazing job on issue #13, and he's really been able to capture Kara's character the way that Mahmud has established it, but at the same time bringing his own cool look to it. I'm thrilled to be able to work with Sami on my first solo issue.
But after the Super-crossover, we're going to see the second act of the Worldkillers and really, finally answer the question of how Kara's father's experiments on her were tied to his experiments on the Worldkillers, and what that means for Kara and for her powers and for her evolution, not just as a character but literally, her biological evolution. That's a tease I can give you there. And evolution, with the Worldkillers, is key as well, because we knew that they grew from embryos to what we saw in issues #5, #6 and #7, but there's nothing to say that they won't stop evolving.