**SPOILERS BECAUSE IT'S HARD NOT TO WITH THIS ISSUE**
"Wrath of the First Lantern" has gone on too long. And that's after "Rise of the Third Army", the 'crossover' that went nowhere. Since last October, the Green Lantern team has been building toward this epic ending, but it's been diluted by time. There's no getting around that.
Green Lantern Corps #19 -- also known as Part Ten of this everlasting story -- is your standard going-through-the-motions issue that doesn't really know what it's doing while we wait for Green Lantern #20. The First Lantern, Volthoom, isn't around much, and John Stewart's minuscule C-story about reassembling Mogo suddenly becomes priority number one. The storytelling is erratic at best.
Mogo is a character that changes based on what's needed. First, he was simply a Green Lantern who happened to be a planet. Then, he became the place where GL rings are forged. Now, he happens to be able to encase large numbers of Green Lanterns within pieces of his planet crust to protect them from Volthoom's attack. How? Not explained.
Oh, and then there's the big old battle of the Green Lantern's Mogo saved against the Yellow, Black, and Red Lantern avatars of themselves...which turn out not to be Volthoom, but Mogo trying to teach everyone a lesson about being better than "what if?"s.
The entire "Wrath of the First Lantern" saga has been about attempting to stop Volthoom before he's able to absorb enough power to rewrite the universe. For some reason, Mogo is able to quarantine his fellow Green Lanterns and involve them in a emotionally charged war against ghosts of themselves without Volthoom noticing. No one seems to be worried that they're taking all this time to go through the motions while the First Lantern is gearing up to wipe existence clean.
Green Lantern Corps #19 is as much a filler issue as you can get. It involves contrived character development based on a continued 'deus ex machina' device. Nothing about the plot is really advanced at all. It's only worth it if you're a completionist.