Magick
I don't know why this double posted! SOrry!
The overall story of this issue is actually intriguing. There's special kryptonite which appears to be imbued with magic; as we all know by now, magic is a big weakness to Superman so magic kryptonite has the potential to really take him down hard. The effects of this two-part kryptonite is actually pretty amusing. Supes becomes childlike and spends a day in the Watchtower playing video games giving himself a long overdue rest from his & Bat's search for all the earthly kryptonite.
The underlying story about Batman's personal feelings toward magick is unusual. I don't see why Batman would deny that magick exists when he studied with Zatarra and has been so close to Zatanna. He and Zatanna butt heads over this subject throughout this issue and it seems so odd that Batman would be this stubborn just for the sake of basically admitting she has power that he doesn't have; he doesn't have this kind of problem with Wonder Woman who has magickally charged armor from the Gods.