Shortly after the plan was settled, Thea and Hal sent out the signal. The Seven Corps converged on Earth.
The Yellow, Indigo, and Blue Lanterns together numbered over three hundred. Thea put all of them under Sinestro's unified command. Saint Walker and Sister Blue were both temperamentally conservative—long on caution, short on aggression. For an offensive operation against an entire dimension, with neither of them carrying the slightest bite, Sinestro was the only option for overall lead.
The Green Lantern Corps was currently being overseen by those First Lanterns, who had returned to serve as Guardians. But they'd been away from the material plane too long and were thoroughly out of touch. All they could do was delegate to the Green Lanterns themselves. The Corps held an internal vote and Hal Jordan became their leader. Without compromising universal stability, he'd pulled five hundred Green Lanterns from across the galaxy for this fight. That made him the head of a real faction now—which was a big part of why he'd bristled at Batman running the show.
Only a handful of Violet and Red Lanterns showed up. As for Orange—Larfleeze was dragged in by Thea through a mix of pressure and bribery after she gifted him ten shipping containers of junk as a Christmas present.
The Justice League turned out in full. The Suicide Squad, full strength. The Rogues, full strength. The Justice League International, led by Booster Gold, stayed behind on Earth. The Bat-family—Batgirl, Batwoman, Batwing—all stayed in Gotham to watch for any move from Black Mask.
The Teen Titans were also benched. The younger generation grumbled loudly, but they got slapped down hard. On the surface, they were left behind to hold the fort. In reality, Thea's off-the-books forces hadn't been touched—Deathstroke and Fiona alone were more than enough to defend Earth.
The operation—codenamed Justice Eternal—officially began. Everyone assembled. They'd transfer through the portal in waves, five minutes apart.
Madam Xanadu and Old Ma stayed on Earth. Earth-3 had Zatanna and her father's support; Mr. E, working alongside several others, put in half a day's effort and finally managed to summon Thea's projection.
This was Earth-3's Detroit. Same name, different location—it was in Europe on this side, a thinly populated city.
The projection glanced around. She had energy distributions to lay out for the Lantern rings, and after that she needed to suppress the local world-will. She exchanged a few quick words with Superman and Diana, then teleported out—heading for this universe's Mars. A lot of her work couldn't be disturbed, and an uninhabited Mars was the best fit.
With her gone, it wasn't long before the Seven Corps rings—gone dark for so long—lit back up.
Superman and Supergirl went to full vision range and thoroughly scouted this Earth.
Superman looked first at this world's Fortress of Solitude. Confirmed—packed with Kryptonite, heavily guarded, every defensive system active. A silent ambush was off the table.
He relayed what he saw to Batman. Batman agreed that throwing themselves at stacked defensive systems was stupid. Krypton sat above Earth on the tech ladder—no question. Luckily he had plenty of fallbacks. "And the Watchtower? How's its defense?"
Superman turned his attention to the square-cornered Watchtower. Apparently to keep distance from Ultraman's Fortress of Solitude, Owlman's Watchtower wasn't in orbit—it sat on the far side of the Moon. Superman had to search for a bit before he spotted it.
"The outer shell is wrapped in a thick layer of lead. Can't see inside..." Superman gave Batman a flat look. How does this Owlman have the exact same tics as you?
Batman pretended not to catch the look. "Where's each enemy right now?"
Superman and Supergirl did another sweep. "Ultraman should be in his Fortress. Owlman seems to be... on a date with Superwoman? Power Ring is in the Black House with government personnel. Johnny Quick is in Central City. Deathstorm isn't tracking—he may be inside the Watchtower. Ocean Master is in the Atlantic."
"We could stage some small incidents to draw them out and pick them off one at a time," Mister Terrific suggested. Some supported it. Some didn't.
Supporters figured leveraging their numbers to pick opponents apart was sound. The opposition argued it was hard to execute—they didn't know what kind of communication systems the enemy had. A single wrong move could trigger a full response, and any full engagement would cost them initiative.
"Strike the Watchtower. I need more on them." When discussion didn't converge, Batman dropped democracy and simply gave the order.
Who was going? They needed flight capability and the ability to survive in space.
The Seven Corps were the obvious choice, but Sinestro sat still. As commander of the three Corps, he acted as if he hadn't heard. Hal was also fed up with Batman issuing orders unilaterally. Normally it was fine, but he had five hundred Green Lanterns behind him now. If he just went along like a good foot soldier, what would his Corps think?
Violet Lantern Carol Ferris, as a Star Sapphire, chose to stay in sync with Green. Orange Lantern Larfleeze was very satisfied with Thea's Christmas gift. He was huddled in a corner furiously writing—adding to his wishlist of future gifts. He wasn't listening.
On Earth's side, Superman and Supergirl were too recognizable to move. Diana was too high-caliber to spend early. Barry and Aquaman couldn't fly. Things got quiet.
At the critical moment the Red Lantern Corps stepped up. Their leader—barrel-chested, with a face straight out of a horror film—growled, "Atrocitus doesn't care about your war. I'm here to pay back a debt. I fight one battle, then I leave. Speak, Earthling. How do you want me to fight?"
Batman ignored the tone. Whether he'd jot it down in a little black book afterward, hard to say. He thought for a beat. "You pretend to be passing through space, then hit the Watchtower. Ideally, draw whoever's inside out. Can you do it?"
Sister Blue offered to teleport them to a distant point, from which they could fly back in as if passing through. Atrocitus didn't love the sneaky angle, but as he'd said—he was here for a fight to clear a debt to Thea. Who to hit and how were details.
He nodded. Sister Blue teleported them out. Less than ten minutes later, the heroes with super-vision saw Atrocitus charging Moon-side at the Watchtower with Dex-Starr and his subordinates.
Fair to say the Red Lanterns looked absolutely terrifying—all of them, wildly varied forms, unmistakably alien. Nothing in them read as "the good guys." Deathstorm, hunkered down in the Watchtower doing research, picked up nothing unusual.
In this universe, the dominant note was evil. A few evil aliens passing through was nothing new.
With zero awareness that this was the curtain-raiser on a full-scale war, Deathstorm floated out.
In Thea's original universe, Firestorm had been the superhero formed by Ronnie Raymond and Martin Stein fusing through the Firestorm Matrix.
Earth-3's Deathstorm was built by mad scientist Martin Stein, who used the Matrix to bind Ronnie Raymond's corpse to himself, creating a supervillain.