"Twilight of the Apprentice" has the return of Maul, who gives the Seventh Sister a brutal death and the Fifth Brother an impaling, as well as managing to corrupt Ezra enough that the boy can open a Sith holocron by himself, andblinding Kanan. And not only that, but we finally get the fight we've all been waiting nearly a decade for; Ahsoka vs. Vader. In the end, it's ambiguous as to whether or not Ahsoka died or once again embarked on a road not taken, but this is the end of her story.
The Season 3 trailer from Star Wars Celebration Europe 2016, full stop. We get to see the promise of Imperial defectors to the Rebellion, including Wedge Antilles with the help of a new Fulcrum, the first onscreen appearance of Governor Pryce, the crew of the Ghost working with Azmorigan and Hondo Ohnaka, Mandalorians on both sides of the conflict, a creature called the Bendu voiced by none other than Tom Baker, more Cham Syndulla, Darth Maul training Ezra in the dark side, Nightsister Magik somehow possessing Kanan and using him to fight Maul, Rex, Kanan and Ezra taking on an army of battle droids, Sabine getting a jetpack and the flippingDarksaber, Dark Trooper droids, what appears to be the Outrider, Ezra's new haircut... and GRAND.ADMIRAL.THRAWN.
The second Rebel Beat commercial reveals that both Ezra and Sabine get possessed by the Nightsister Magik, and Ezra finds that the Darksaber was kept by someone (who may just be using it as some decoration or to pay respects to rather than actually use it) rather than simply lost at some point. And we already know from another teaser that Maul gets possessed as well.
The midseason trailer for Season 3:
As mentioned in theVisual Guide for Rogue One, Mothma and Saw appear as the former has become a public enemy number 1 due to publicly calling out Palpatine (but on the bright side, this means she has more time to focus on personally helping the Rebellion become the Rebel Alliance) and the latter conducting an investigation on Geonosis about the Death Star (and will inevitably be poisoned).
Thrawn being surprisingly good at combat against the Dark Troopers from "The Wynkahthu Job", going to Geonosis backed by Death Troopers, as well as implicitly saying he is going after Mothma and the growing Rebel fleet (and he's already found Atollon... but for some reason, the base is protected by possibly the Bendu's powers); the rebels are too late to stop the production of TIE Defenders.
We return to Lothal, where it seems we're going to get more Character Development from Kallus as time gets closer to his cover being blown, as well as him going to Ezra's tower seemingly alone for an unknown reason.
Zeb (who is finally using his bo-rifle in staff mode again), Chopper, and AP teaming up to fight the Warhead; a possible Yularen appearance; the return of Wedge; Sabine gaining more devices and becoming more skilled (with the help of Kanan and Rau) so that she can rally her people with the Darksaber, eventually gaining the support of a splinter group possibly led by her mother, as well as somehow losing the Darksaber to Saxon but taking up Kanan's saber to fight him, and of course, Ezra and Chopper journeying to Tatooine, where Maul and Obi-Wan finally face off.
The last scene of "Twin Suns": Obi-Wan watching the Lars homestead from a distance, and Beru is heard calling for Luke — and then we see him, from a distance, running home. It's not an action scene, but with who's in it and where it takes place, it most definitely qualifies.
By the way, the Season 4 teaser in Rebels Recon showed the helmets of Clan Wren, a Nite Owl, and a Protector, lying around like it's a makeshift graveyard or a pile of skulls in a post-apocalyptic wasteland
The revelations at Star Wars Celebration 2017 that Warwick Davis is voicing Rukh, Thrawn's bodyguard (and later his assassin) from Star Wars Legends. Soon followed by Filoni breaking the news that the fourth season will be the last. And then the trailer, with Hera's narration hinting at an ominous end to the Rebels' story, Ezra riding a huge wolf with an unconscious Sabine, the new base on Yavin 4, explosions, Hera and Kanan looking as if they're about to kiss, Saw Gerrera, Bo Katan, Hera entering hyperspace through an Imperial hangar bay,Kallus' new look, epic battles, Hera in X-Wing gear, Bo Katan wielding the Darksaber, and the implication from Kanan's narration that he and Ezra might not survive.
The September trailer showed Lothal taking a toll from the Empire's environmental abuse and being further ravaged by the battle between the Alliance & the Empire there (with a shot of the Ghost crew watching what appears to be missiles falling towards Capital City), Hera leading X-Wings against the Lothal blockade and personally fighting Rukh, growing tensions between Saw and Mothma, members of Clan Wren being disintegrated by what is likely Sabine's superweapon on a chicken walker, Bo-Katan and her Nite Owls turning against Sabine and co. due to losing faith, numerous Mandalorian clans (including one that bears a similar palette to Boba's own armor) bowing to Bo-Katan wielding the Darksaber, Tarkin telling Thrawn that his TIE Defender project is at odds against Krennic's "Stardust" project, the return of the white lothcat atop the white lothwolf and a Cerebus Retcon of the eeny-meeny-miney-mo poem from Season 1, Ezra meeting a pack of lothwolves and his eyes looking like hyperspace like they did with the purrgil, Kanan and Hera finally coming to terms about their relationship, and Ezra calling back to what Yoda said about how they choose to fight; maybe they're choosing the wrong way.
As you'd expect from the final trailer, the midseason trailer giving us our first look at the Grand Finale tops everything we've seen before. Thrawn has ordered a full bombardment of Lothal, Rukh fighting Kanan and Zeb, the return of Wolffe and Gregor, a gigantic loth-wolf with Ezra's eyes that dwarfs the loth-wolves seen before, the return of Ahsoka's convor, a mosaic depicting the Father, the Son, and the Daughter from the Mortis arc lighting up when Ezra touches it, Kanan gets a haircut, and Ezra faces off against Palpatine himself for the fate of Lothal, with Ian McDiarmid returning to the role.
Ezra activating the mural of the Father, Daughter, and Son of Mortis to open the Lothal temple, whereupon he finds himself in a vast empty field filled with stars, like his vision of Yoda from the first season, where, as he's walking through, hears the voices of characters from the past, present and future in EVERY canon installment since the Disney buyout and beforehand, including all the main saga movies, Rogue One, and The Clone Wars. Awe-inspiring is the only word to describe it.
A subtle part of the above: right as Ezra flies through the portal ringed with running lothwolves, if you look through the portal behind him at the right moment, for a split second, you can see the silhouettes of his parents.
Ezra pulling Ahsoka through space and time to save her from the Malachor explosion. That's right, the power of the Force can now be canonically used to TIME TRAVEL and change the future.
Ezra's plan to summon a massive pod of Purrgil to wipe out the blockade surrounding Lothal was something NO ONE saw coming.
