A few months after the end of the Hate Plague, the Decepticons launch a full-on assault on Autobot City to steal the key to the Plasma Energy Chamber on Cybertron. The Autobots retrieve the key, but a blast of plasma energy sends their ship crashing on the planet Nebulos. The Autobots and Decepticons ally themselves with the native Nebulons and merge themselves with their tech to become Headmasters and Targetmasters. With their new abilities, the Autobots and Decepticons wage their final battle to either usher in a new golden age for Cybertron... or destroy it.
Tropes
- All of Them: Optimus warns Kup that an army of Decepticons are coming to invade Cybertron. When Kup asks how many Decepticons are arriving, Optimus simply says "All of them".
- Big Damn Heroes: The Autobots are either captured or rendered offline by the Decepticons, and Galvatron is possession of the key to the Plasma Energy Chamber and is prepared to destroy the entire solar system. All hope seems lost until Spike and Cerebros arrive on Cybertron with their latest creation; Fortress Maximus.
- Bloodless Carnage: Daniel is mauled by Snapdragon to the point that he requires a life support system to keep him alive. However, Daniel doesn't have a scratch on him. Not even his clothes are damaged after being chewed on by a robotic dinosaur.
- Grand Finale: The Autobot and Decepticon war reaches its climax as the Decepticons plan to unleash the plasma energy from Cybertron to destroy Earth and the entire solar system. Thanks to Spike and the Nebulons, the Autobots are able to draw the excess energy from the Sun, drive the Decepticons into the depths of space, and usher in a new golden age for Cybertron.
- Last Episode, New Character: The finale for the show also had to serve as vehicle to promote the 1987 toyline. As a result, over 46 new named characters had to be introduced over the course of the three episodes. At a few points, some characters only showed up for one or two scenes before dropping out of the story.
- Malicious Misnaming: When engaging in a firefight with the Decepticons, Daniel insults Cyclonus by calling him "Cy-clown-us".
- My Significance Sense Is Tingling: Optimus confesses to Ultra Magnus that's he's been having vague visions since he emptied the Matrix of Leadership to cure the Hate Plague, and that all he knows is that something big is going to happen very soon.
- Omniscient Morality License: Alpha Trion tells Optimus that Vector Sigma was the one who told Galvatron about the Plasma Energy Chamber and arranged everything in motion to secure a new golden age for Cybertron. Optimus is shocked that Vector Sigma would risk putting that kind of power in Galvatron's hands, but Alpha Trion tells him that Vector Sigma is far more advanced than either of them and knows what best for Cybertron.Optimus: Alpha Trion, that makes no sense!
Alpha Trion: Do not question Vector Sigma's motives! The parameters of its thought matrix are greater than you can imagine. - One-Man Army: Sixshot's only appearance in the three-parter has him transform into each of his six alt-modes and effortlessly take out the Aerialbots in a matter of seconds. Galvatron even refers to him as a "one-robot army".
- Only Flesh Is Safe: The plasma energy is devastating to mechanical life by overloading anything that converts matter into energy. Organics beings are immune to this effect, which is the reason Vector Sigma arranged to have the Autobots land on Nebulos in the first place. It's only thanks to Spike recruiting the aid of the Nebulons that plasma energy released from the overloading Sun can be merged with Vector Sigma and restore Cybertron to its former glory.
- La Résistance: The Nebulons the Autobots encounter are leading a resistance group against the tyrannical rule of Lord Zarak and the Hive. By the end of the story, the Headmasters return to Nebulos to help destroy the remnants of the Hive's machines and free Nebulos once and for all.
- Star Killing: Galvatron's plan is to transport Cybertron into Earth's solar system and to release all plasma energy from the Plasma Energy Chamber so it can cause the Sun to go supernova, wiping out the entire solar system in the process.
- A Twinkle in the Sky: The plasma energy strikes Scorponok as he carries the Decepticons away from Cybertron. This causes Scorponok to be launched deep into the depths of space, leaving behind a small twinkle in the night sky as he leaves Cybertron's orbit.
- Twisted Echo Cut: The final scene of the episode has Optimus and the Headmasters preparing to bring peace to Nebulos, before cutting to Galvatron and Zarak onboard Scorponok bemoaning their current situation:Optimus: Cerebros, when the last of the Hive's evil is gone, you shall remain here in peace as this world's guardian.
Cerebros: Thank you, Optimus Prime. It's a miracle.
[cut to Galvatron and Zarak piloting Scorponok]
Galvatron: It's a miracle we finally got this flying junkpile of yours stabilized! - The Worf Effect: The Aerialbots, depicted as a powerful combiner team in the last two seasons, are quickly taken out in short order by Sixshot (albeit one-by-one instead of as Superion) to showcase how cool all his different alt-modes are for the audience.
- Would Hurt a Child:
- Snapdragon viciously mauls Daniel before tossing him to the ground, leaving him with injuries so severe that he requires emergency life-support systems to keep alive.
- Daniel and Arcee are taken hostage by Zarak, who demands they hand over the key to the Plasma Energy Chamber. Zarak has Monzo torture Daniel by ripping off the arm to his exo-suit to get Arcee to comply, which she quickly does so.
- Wrap It Up: By this point in the franchise, sales for the toyline were starting to decline and it was clear that funding an entire fourth season wouldn't be profitable for Hasbro in the long run. To give the show of sense of closure and ensure the latest toyline was still promoted on the show, Hasbro commissioned Sunbow to have season four of the show be a single five-part storyline. However, budget cuts eventually reduced the episode count to three, leading to a rather condensed final season.
