The Mandalorian season 2, episode 4, "Chapter 12: The Siege" ends with Moff Gideon in a new, Darth Vader-like suit of armor overlooking similar black-armored suits, which could have significant implications for the Star Wars franchise. Even though Emperor Palpatine was killed and the Empire officially fell five years before the events of The Mandalorian, Moff Gideon and his Imperial remnants are still operating as if they've only been temporarily set back.
Things have fundamentally changed in the galaxy - particularly in the Core Worlds, as the New Republic pilot Carson Teva has duly noted - but the Outer Rim continues to be Star Wars' Wild West. The Empire couldn't and still can't control the region, and neither can the New Republic. So it's fallen to warlords like the Mining Collective on Tatooine and Moff Gideon on Nevarro and the surrounding systems. But unlike those other warlords, Moff Gideon and his Imperials have something much bigger planned.
A grand scheme involving Baby Yoda, midichlorians, cloning, weapons, and a fleet, the Imperial remnants are making a large push into the Outer Rim territories in order to re-establish the Empire's dominance. However, while there are certainly a number of stormtroopers and officers loyal to the cause, and to Moff Gideon, they already lost the war. It would seem they need some sort of help to achieve their goal, which is where Moff Gideon's new Imperial battle droids come into play.
Moff Gideon's Dark Trooper Army Explained
After appearing via hologram in the previous episode, Moff Gideon made his season 2 debut in-person in The Mandalorian's "The Siege", in which he was standing comfortably aboard his light cruiser ship. At the end of the episode, an Imperial comms officer informed Moff Gideon that their spy had successfully planted a tracking beacon aboard the Razor Crest, which will presumably follow Din Djarin to Ahsoka Tano on Corvus. It wasn't just the tracking beacon that surprised viewers but also the armored suits surrounding Moff Gideon in the bay.
"The Siege" ended with a tease of dozens of black-colored armored suits, which were being worked on by engineers - with Moff Gideon himself wearing one of the suits, or at least something similar to it. At first, it looked like Moff Gideon designed his own Darth Vader-like battle armor, but that's not the case. Those suits are actually Dark Troopers, confirmed by the episode's audio description: "Rows of similar compartments sprawl throughout the bay, with an engineer in white coveralls tending to immobilized Dark Troopers contained within."
Dark Troopers are one of many stormtrooper variants in Star Wars and have a long history in the Expanded Universe, but what sets these ones apart from the likes of Death Troopers and Purge Troopers, both of which resemble Gideon's suits and have been established in canon through Rogue One: A Star Wars Story and Jedi: Fallen Order, is that Dark Troopers are battle droids. They're not human, like the Death Troopers, or former clones, like the Purge Troopers. They are the Empire's version of the Separatists' droid army, but much, much better.
Dark Troopers In Star Wars Canon & Legends
Like many characters, stories, and various other elements of Star Wars, the Dark Troopers first appeared in the Expanded Universe - namely in the video game Dark Forces - before being reintroduced into canon, in Star Wars: Commander. Through Dark Forces, Empire at War, The Force Unleashed, and particularly the Battlefront games, the Dark Troopers went from being experimental droids to a terrifying force in the galaxy. They were initially designed by General Rom Mohc of the Arc Hammer facility, who used similar technology that created Darth Vader's suit to turn residual clone troopers into cyborg-like fighters around the time of A New Hope.
Those cyborg clone troopers were retconned to be the original Dark Troopers, but later models (Phases) were entirely battle droids - all of which were created by Rom Mohc. Phase 1 consisted of sentry-like Dark Troopers that came equipped with vibroswords - essentially longer versions of Din Djarin's vibroblade - while Phase 2 Dark Troopers were more inline with what the super battle droids were like in the Separatists' droid army; those versions had sturdier armor, assault canons, and jet packs, and they were used to infiltrate Rebel bases around the galaxy. The final version, Phase 3 Dark Troopers, took everything that worked in Phase 2 and expanded on those elements. They were larger and came outfitted with indestructible armor; they also had additional weaponry that enabled them to penetrate virtually any defense system, but unfortunately, they were hardly used in battle since the Arc Hammer was destroyed in the time between A New Hope and The Empire Strikes Back (again, in the Expanded Universe).
While the Dark Troopers were widely used in Star Wars video games in the 1990s and 2000s, they have only appeared one other time in Disney's canon: in the 2014 video game Star Wars: Commander. So not much is known about the canon version of the Dark Troopers yet, except for what was shown in The Mandalorian season 2, episode 4. Some things can be gleaned from their brief appearance, though, such as them resembling the Phase 3 Dark Troopers rather than Phases 0-2, and that they can be designed as exoskeletons given Moff Gideon was wearing his own suit.
How The Dark Troopers Factor Into The Mandalorian Story
When the Empire lost the Battle of Jakku and subsequently signed the Treaty of Coruscant, that ended the Galactic Civil War, not everyone put down their weapons. Moff Gideon, who was once an ISB officer, and his Imperial remnants are loyalists to the end, not only to the Emperor but to what the Empire itself stands for. And so, they continue to fight to regain control of the galaxy, which lays the foundation for the First Order's arrival decades later in the Star Wars sequel trilogy.
In the meantime, Moff Gideon will continue to push his agenda that includes wielding the Darksaber as well as experimenting with midichlorians and cloning, hence the inclusion of Dr. Pershing. Part of that agenda also has room for the Dark Troopers - which could very well be exoskeletons rather than full-on battle droids, but that hasn't been confirmed yet. Given that Moff Gideon himself is outfitted with similar armor, it stands to reason that he will use the Dark Troopers to defeat the New Republic's forces in the Outer Rim, retake planets like Nevarro and Tatooine, and defeat Din Djarin and Bo-Katan's Mandalorians, who are amassing a force strong enough to take on the Empire.
Even though Moff Gideon's scientists are trying to extract midichlorians (M-count) from donors, it's unlikely The Mandalorian will have the Imperials attempt to create new Purge Troopers - Force-sensitive stormtroopers who were tasked with hunting down and killing the Jedi. Since "The Siege" audio description explicitly refers to the Dark Troopers as being "immobilized," that heavily implies they are robots, similar to the Expanded Universe's earlier Dark Trooper models. Those troopers were capable of taking out entire Rebellion bases with little to no casualties on the Empire's side. If Moff Gideon is planning a blitz in the Outer Rim, then the Dark Troopers are his best bet at winning.