What do you call world-building when it’s built entirely out of worlds that have already been built? I wouldn’t call it cinema; it might be closer to Lego with attitude. Zack Snyder’s “Rebel Moon — Part Two: The Scargiver,” like his “Rebel Moon — Part One: A Child of Fire,” is a sci-fi action fantasy so familiar and generic, so borrowed from and inspired by other things — it’s the 1977 “Star Wars” meets “Seven Samurai” meets “The Lord of the Guardians of the Rings of the Galaxy” — that it’s already the theme-park version of itself. Yet compared to most of the media, I was kind to “Rebel Moon — Part One.” Released just four months ago, it was an oversize banquet of fanboy fast food, not a film to take seriously, but I couldn’t deny that I found it highly watchable, unlike the countless critics who seem to feel that Zack Snyder has become The Enemy Of All They Stand For.

Having cut “Part One” some major slack, though, even I will say: “Part Two” has less of interest going on in it. It’s just an extended countdown to the big showdown, with Snyder devoting scenes to “filling in” characters who still come off as human action figures. Djimon Hounsou as Titus the fallen general-turned-recovering warrior, Doona Bae as Nemesis the cyborg sword master (who wields a weapon that, I’m sorry, is literally a lightsaber), Michiel Huisman as Gunnar the handsome but slightly wimpy love interest, Anthony Hopkins as the voice of Jimmy the droid — there are no hidden levels to these characters. Sofia Boutella’s Kora remains a two-layer cake of Fierceness, with an inner frosting of Vulnerability, who always returns to Fierceness.  

Put “Part One” and “Part Two” together, and it’s clear that “Rebel Moon” is a four-hour movie that could have been told in two hours. It’s not really “epic” — it’s just stretched-out. In the first half of “Part Two,” most of which is set on the amber-waves-of-grain medieval farming moon of Veldt, the film just kind of sits there, treading grain, with a soundtrack of New Age Jungian music as the farmers harvest their crop and ready themselves for battle. There are flashbacks that shore up the characters’ valor and fill in the things they feel guilty about (like the fact that Kora, when she was a royal bodyguard and the adoptive daughter of the Imperium commander Balisarius, was ordered to assassinate Princess Issa).

But it’s all working up to the rebels-meet-the-fascists battle royale, and when Snyder is in his action element, as he is in the last 45 minutes of this movie, he can be as dazzling a genre stylist as James Cameron was in the ’80s. I can almost imagine a trailer for “Rebel Moon — Part Two” with the narrator intoning, “In a world where every movie blows up real good, Zack Snyder really blows this shit up good.” He’s a master of disaster, of putting the metal on screen, of dreaming a dream and watching it detonate. This time, though, even the fanboys may have to convince themselves they care.

At the end of “Part One,” Kora, leading the motley crew she’d gathered to fight the Motherworld, had won a duel to the death with Atticus Noble, the evil admiral who, as played by Ed Skrein in a fade topped by scary Roman Nazi bangs, is like Freddie Mercury as a Shakespearean sociopath. But even though she killed him, the Motherworld technology resurrected him. As “Part Two” opens, his body is still lying in a pool of gel, with wires sticking out (very “Frankenstein,” and also very “Dune”), but he’s utterly alive. He soon proves that he’s back to his old tricks by lifting up his Darth Vaderish black-metal-masked henchman as if Atticus himself were Darth Vader. (The henchman cautiously advocates that Atticus undergo more medical tests; for that advice, Atticus smashes his head in.)

With its force of evil revived, and newly messianic, “Part Two” settles into a plot that could hardly be more basic. Kora and her team return to Veldt, where they prepare the noble farm community for battle. Atticus and his military machine plan their own return visit so they can smash the rebellion, with extreme prejudice shown toward the mission of assassinating Kora. She’s the Scargiver because of the circular chest wound she gave to Atticus during their big duel.

The gigantic Motherworld ship arrives just as it did last time, hovering over Veldt in broad daylight, only now Kora is prepared. She, along with Gunnar, infiltrate it in a mini-ship of their own. Once inside, she plants strategic explosives and seeks out her nemesis, and the film cuts to the battle below, which oscillates between rock ‘n’ roll sci-fi gunfire and hand-to-hand savagery and the immensely gratifying ain’t-that-a-kick-in-the-head sight of war ships blowing up from inside, all set to one of those neo-Hans Zimmer scores of droning dread.

“Rebel Moon — Part Two: The Scargiver” is a storytelling mediocrity, but as spectacle it has tumult and rhythm. It gives nothing away to say that in the end, the forces of good triumph. But what surprised me is that just as “Part One” concluded with the twist that Atticus Noble could be revived, “Part Two” ends with the revelation that a key character we thought was dead is not. This is obviously the set-up for “Part Three,” so if you thought we were done with Zack Snyder and his deliriously derivative intergalactic Netflix action daydream, think again. There’s a question that now has me in suspense more than most of the Marvel-movie teasers do. And that’s this: What movies will he knock off next time?