Forever Evil itself. Like Trinity War and unlike, for instance, Superman: Doomed, Blight takes place only in the individual series and not in any specials or annuals, so its equally possible to read it in its own Blight collection or between the various individual series collections, and with much flipping back and forth, I did the latter.
What follows is in part a review of the Blight story as a whole and in part a review of Justice League Dark Vol. 4: Rebirth of Evil, which collects the Justice League Dark chapters of Trinity War and Blight. I'll subsequently review the other collections involved with Blight in a similar way, examining the overall story but also how it plays out in the individual book.
As befits the menagerie of magical characters who populate the story, Blight is in part a wonder to behold and in part total chaos. It is unlikely to replace in your mind, perhaps obviously, something like Alan Moore's tour of Heaven and Hell and DC Comics's mystical characters in his legendary Swamp Thing. But if you've been a fan of the New 52's attempt to revitalize the DC Universe's "dark" corner, then there's some joy in this prolonged story that teams classics John Constantine, Swamp Thing, and Phantom Stranger with new(er)comers like Pandora, Nightmare Nurse, and Zauriel (plus, to the point of wonderful absurdity, Deadman in the body of a 1990s-style, hook-handed, zombie Aquaman) in a variety of weird and far-flung adventures.
That Blight is "prolonged" is its strength and its weakness. If "Blight" were the ongoing story in the now-delayed Dark Universe title or some sort of "dark" equivalent of Mark Waid's 2007 Brave and Bold -- which told one story with a variety of DC Universe characters passing in and out -- it might be regarded as relatively ambitious and epic, the kind of long-form storytelling we don't tend to see in comics these days. As a multi-title crossover, however, there's a need to recap the major story beats each issue, which gets repetitive and ponderous; I also feel less forgiving in a crossover of the story's more tangential aspects, which come off not as curious asides but rather page-fillers to keep this or that series involved.
[Review contains spoilers]
One can neither read Trinity War nor Blight in Justice League Dark Vol. 4: Rebirth of Evil and really know entirely what's going on. The Dark issues of Trinity War (issues #22 and #23, Trinity War parts 3 and 5, the first and second chapters of this book, both written by Jeff Lemire) do place some emphasis on the Dark characters, but not a lot more or less than the rest of Trinity War. Issue #23 has a better recap of the action than issue #22, but in all the major twist of Trinity War, leading into Blight, is over in Justice League instead.
Blight functions better here in that Dark issues #24-25 are parts 1 and 2 of Blight, uninterrupted, and issue #29 is the conclusion, part 18(!), so the reader is oriented in the start and end. Also John Constantine's personal demons-made-manifest that appear in Part 1 reappear in Part 18, and an important conversation that Constantine and Zatanna have in issue #28, Part 14, is referenced in issue #29, Part 18, so the trade feels to have some continuity. At the same time, Constantine is seemingly killed between issues, the Phantom Stranger seems to have betrayed the team between issues (and then not), the team is captured between issues, and Constantine escapes capture between the issues, so equally in reading Dark on its own one signs up for part and not the whole story.
Though called "Blight," the story is comprised of two acts, split ten issues and eight issues, the first of which actually involves the evil Blight entity and the second one not at all (Dark is four parts of act one, two parts of act two). Though the second act is set up early in the first, the structure is still surprising, and lends itself to Blight's sense of neverending-ness, since the story is called "Blight" (just when you think Blight is defeated -- more!). At the same time, Dark is also helped immensely by the villains of the "Project Thaumaton" story being Felix Faust and Nick Necro, late of Justice League Dark Vol. 2: Books of Magic, making the Dark parts feel relevant to this title. Unfortunately, long-time Dark artist Mikel Janin bows out just before this point, so we get a silly-looking Faust instead of Janin's creepy one (Blight's art, on the whole, is strong early on under Janin, Aco, and Fernando Blanco, but weakens in the end with Beni Lobel, Vicente Cifuentes, and Francis Portela).
The story starts with the vague premise of Constantine being unable to find the kidnapped "old" Justice League Dark because of some sort of evil "static" in the mystical atmosphere that eventually gains sentience as Blight. (Though Blight is at times repetitive, one benefit is that the origins and motivations of Blight get clearer in the retellings.) Setting out to defeat Blight, Constantine gains a motley crew of Nightmare Nurse, Swamp Thing, and the Trinity of Sin Pandora, Phantom Stranger, and Question; Question drops out early, but they're later joined by Deadman (of sorts) and the angel Zauriel, among others. They are, after a fashion, a "new" (if short-lived) Justice League Dark, which further makes the story feel title-specific. For me any book without Frankenstein is poorer for it, but I enjoyed seeing Constantine leading this new team if only for an abbreviated (eighteen-issue) period.
Even as there was much in the story I enjoyed, most off-putting was the built-in assertion that Constantine is seeking his Dark teammates to find Zatanna, because he loves her. First, a foible of the crossover is that Constantine must avow his love for Zatanna every chapter to keep new readers up to date, such that Constantine comes off like a pining, lovesick puppy. Second, while I wasn't admittedly a Hellblazer reader, a John Constantine motivated by pure un-ironic love doesn't read like legendary bastard John Constantine to me. It's obvious not far into the story that the only way this can end without treacly melodrama is for Zatanna to reject Constantine, which she does almost as soon as they're reunited.
As well, after almost eighteen chapters of build-up (and plenty of admirable work), writer J. M. DeMatteis's conclusion is unfortunately a let-down. I give DeMatteis's credit for working an element from the first chapter into the last, but for a story that had so many elements that recurred throughout, that the return of Constantine's personal demon was never foreshadowed is surprising, and made the ending feel like a deus ex machina (neither is Cifuentes's art entirely clear in the important scenes with dual Constantines). I also might have expected a little more role for all the new Dark characters in the story's end, instead of just Constantine and Zatanna.
That said, I think what J. M. DeMatteis has been doing on Phantom Stranger is great, and I've also found some to like in Ray Fawkes's Constantine and Pandora; all of that ended up for me with Blight being enjoyable, even if I kept glancing ahead in shock at how much I still had left to read. By and large DeMatteis did fine scripting the "Blight" parts of Justice League Vol. 4: Rebirth of Evil, and my only hesitation continuing to the next volume is that I haven't been a fan of Andres Guinaldo's art so far; the difference in my reaction to Mikel Janin's and Vicente Cifuentes's chapters here make clear to me the difference the artist makes on this title.
[Includes variant covers]