It’s hard to pick a single part. The whole thing was great. I did particularly enjoy the random switch to Sapphire / Blue for some of the GL. Hope to see more of that story unfold.
Pretty much everything. John meeting the Source. Hal getting everyone to will their rings back into existence. Simon tapping in to all the deceased lanterns. This issue was quite the wild ride.
I suspect there will be more of Kilowog’s situation. Beyond that, probably Jo getting properly integrated into the Corps instead of lone-wolf style. Maybe helping Simon deal with the ghosts of the former lanterns and Keli waking up.