Warning! Spoilers for Dark Nights: Death Metal #3 below!
When it comes to grotesque, horror-themed monstrosities in the DC Universe, the Black Lanterns are in a league of their own. First appearing in the Geoff Johns Green Lantern tie-in event Blackest Night, the Black Lantern Corps. is comprised of undead foot soldiers powered by Black Lantern power rings. But rather than bring the wielder's imagination to life through hard-light constructs like the Green Lantern power rings, the black rings are a fashion accessory of necromancy. And in Scott Snyder and Greg Capullo's headbanging epic Dark Nights: Death Metal, Batman proves to be a true master of the Black Lantern ring in his war against the Batman Who Laughs and his twisted Dark Knights.
Unlike standard zombies Black Lanterns don't feed on brains, they feed on hearts--or rather the emotional energy of lifeforms that they harvest through their hearts. They also retain the memories and abilities of their former selves and are capable of speech, but this is merely emotional warfare. The Black Lanterns themselves aren't truly sentient; they are nothing more than puppets stuffed with dark matter. And the one pulling the strings is Nekron, the avatar of death. During their reign in Blackest Night, Nekron and his Black Lanterns killed dozens of heroes and villains throughout the DC Universe, and just when it seemed as though Earth's defenders had the upper-hand on the galactic necromancer, Nekron resurrected the corpse of the recently deceased Batman, triggering an emotional response that turned every previously reborn/rebooted hero into Black Lanterns themselves. Or so it seemed.
As it turned out, Batman wasn't actually dead during the events of Blackest Night. In fact, he wasn't alive either. After confronting Darkseid in Grant Morrison's Final Crisis, Batman was hurled into the past Cloud Atlas style by something called the Omega Sanction--a rather odd ability of Darkseid's that traps his target in an endless loop of past lives, each one full of misery. Though the corpse that Nekron transformed into Black Lantern Batman didn't really belong to Bruce Wayne, it is the events of Final Crisis and Batman's journey through time that eventually lead to him becoming the greatest Black Lantern of all.
During the first installment of Snyder and Capullo's Metal saga, it is revealed that Bruce stumbled onto the sights of the bat-god Barbatos while Quantum Leaping through time. Realizing that the bearer of the bat-emblem would make the perfect envoy, Barbatos spends centuries grooming history in order to turn the Dark Knight into his ticket out of the Dark Multiverse--a patchwork of nightmare realities that even include a universe where the Black Lanterns won. The ritual worked, and Batman was transformed into a portal releasing a legion of Nightmare Batmen from the darkest realities of the Multiverse. Barbatos is eventually defeated, but the Source Wall is destroyed in the process and a much greater threat, Perpetua, is released.
Not long after being freed Perpetua, a fallen goddess from the Multiverse prior to our own, rebuilds reality in her own dark image, recruiting the Batman Who Laughs as her envoy. Drawing energy from the Dark Multiverse, Perpetua, and her new messiah easily conquer the vast majority of the Multiverse. With only Wonder Woman and a small group of resistance fighters not dead or locked up in hell, it seemed almost preposterous to assume Batman had something up his utility belt to even the odds against forces that powerful. But he had the one weapon even Lex Luthor himself was literally willing to die for--the Black Lantern power ring.
Unlike previous Black Lanterns, Batman seems to actually be fully alive and conscious, though Bruce seems oddly secretive about his "ice cold" body temperature. And unlike the fake Black Lantern Batman in Blackest Night, the one in Death Metal isn't a puppet; he's the puppeteer. While confronting the Batman Who Laughs and his army of dark allies in an open park (where it was aforementioned as the sight of a great battle), Batman turns the tables on his foe by resurrecting the Deadbeats--a Gotham militia massacred during the American Revolution. Not expecting Batman to pull necromancy out of his utility belt, the Batman Who Laughs is momentarily pushed back.
Not only did Batman resurrect the Deadbeats, but he also resurrected Jonah Hex, the infamously disfigured bounty hunter from America's cowboy era. Using Hex's fighting abilities as well as his personal intel on some of America's oldest champions such as Uncle Sam, Batman's undead minions actually seem to exhibit a level of sentience that the previous Black Lanterns never had before. While the zombie hordes in Blackest Night only mimicked the personalities of their living counterparts, Batman's resurrected soldiers (specifically Jonah Hex) actually appear to have a level of free will.
But Death Metal Batman doesn't stop there. He later uses the Black Lantern ring to save Superman from a Darkseid-infused Batman called Darkfather. Bombarding Superman's body with kryptonite, Darkfather planned to infect Superman's decaying cells with Anti-Life, turning him into a mindless weapon. But to Darkfather's shock, Clark easily shrugged off the effects of the Anti-Life machine. Using his Black Lantern ring, Batman was able to take control over Superman's dead tissue and repel the dark matter infection from taking hold. While it doesn't sound as impressive as resurrecting an army of Revolutionary fighters, being able to cancel out the Anti-Life Equation is a feat very few in the Multiverse have achieved.
What's arguably most fascinating about Batman's use of the Black Lantern ring is that Snyder has been very vague as to whether or not Bruce Wayne is fully alive at this point in the story. Superman hints that Batman is keeping a secret from Wonder Woman, and this was mentioned shortly after Diana herself noticed that Bruce's body was ice cold. And when Darkfather shot Batman with his own version of the Omega Sanction, rather than get zapped from the timeline like before, Batman just gets up unscathed. How he's able to do this remains to be seen, but it's likely tied to the Black Lantern ring. With the Batman Who Laughs fusing with a Bruce Wayne version of Dr. Manhattan and becoming an abomination of reality, Batman is going to need to use every tool at his disposal to save the DC Universe from the darkest versions of himself.