In 2007, on the back of a ton of nostalgia for everything that ever happened in the 1980s, DreamWorks released a film based on the popular Transformers toyline that was appropriately enough entitled "Transformers." It was the latest and biggest attempt on the part of Hasbro -- the American company that owns the Transformers property along with G.I. Joe and My Little Pony, among others -- to draw an older audience's interest in the franchise. Starring the "actors" Shia Laboeuf and Megan Fox and "directed" by explosion aficionado Michael Bay, the movie was unconnected to any prior Transformers continuity but it featured new versions of familiar characters, including the four that Hasbro now considers vital to the brand's success: the heroic Autobots Optimus Prime and Bumblebee as well as the evil Decepticons Megatron and Starscream.
The movie was a massive success and led to a major revitalization of the Transformers brand. Obviously, there was a toyline to go along with this movie and it was also a massive success. The movie of course has had several sequels (with accompanying toylines, naturally) which all routinely perform extremely well financially. Now, this is not to imply that these movies are good in any conventional sense of the word (because, uh, they're not) but they're successful and they opened the door for Hasbro and their Japanese counterpart Takara to change the way they do merchandising.
Previously, Hasbro only released one Transformers toyline at a time. In the early 2000s, there were experiments with running multiple lines concurrently, but a consistent glut of unsold product at Wal-Mart made retailers skeptical of this concept and this practice was severely curtailed. After the success of the live action movies, however, Hasbro and Takara flooded the shelves with Transformers products and retailers ate it up. Generally, this included four separate lines: one based on the movies, one based on whatever cartoon was currently airing on television, one meant for kids 3 and under, and one that is in some way related to or based on the original "Generation 1" line from the 1980s. Generally, this last line is geared toward adult collectors who were fans of the original series. The final line is called Transformers Generations and has run since 2010 with various sublines. In 2014, Hasbro introduced Transformers Generations: Combiner Wars.
If you were ever a fan of the original G1 Transformers series, you remember the combiners. Groups of five or six robots united by some type of theme (for example, the Constructicons were six construction vehicles or the Aerialbots were five planes) who merge together to form one giant robot. If you were not familiar with the concept, you are now! Since their inception in the 1980s, the combiners have been some of the most popular and iconic Transformers figures and characters. I mean, come on, they're just cool. It's not enough that they're transforming robots, they also unite to form BIG robots! Basing a line around this popular concept was a no-brainer.
The Combiner Wars toyline saw the return of several teams and characters that had fallen by the wayside over the years. Almost all of the familiar combiners from G1 received upgrades here: the Constructicons, the Aerialbots, the Stunticons (cars), the Combaticons (military vehicles plus, strangely, a space shuttle), the Protectobots (emergency vehicles), and the Technobots (weird futuristic shit with little basis in reality) showed up along with several new combiners based on Optimus Prime, Galvatron, and others. Non-combining characters like Megatron, Starscream, and Shockwave put in appearances as well. The line also featured the first "fan-created" combiner, Victorion. Victorion was the result of a series of polls which determined the character's gender (female, making her the first female combiner in the franchise's history), name (this should be obvious), color scheme (red and green), and a host of other things. The line also featured the first American release of the characters in the Breastforce (no, that's not a typo) combiner subgroup, although this was an online exclusive not available at retail.
Combiner Wars was unique among the Generations lines up to that point in that it was the first of the "nostalgia" lines to get an animated series (if you want to call it that). Previous lines had either comic books or video games backing them up. Hasbro therefore commissioned the Japanese animation studio Tatsunoko to make a cartoon series based around the line. This was...not wise. Comprising 8 5-minute episodes, this series is a mess. It takes place at some unspecified time in the future and does not appear to be connected to any previous continuity. Bizarrely, it also fails to feature the combiners in a way that you would think would be consistent with a series called "Combiner Wars."
The basic outline is that the war between the Autobots and the Decepticons is over. The leaders of the respective factions, Optimus Prime and Megatron, have been exiled from the Transformers' home planet of Cybertron presumably to prevent them from starting the war up again. Cybertron is now ruled by a triumvirate of Rodimus Prime, Starscream, and a Camien Transformer called Mistress of Flame, who are tasked with maintaining the fragile peace and safeguarding a powerful relic known as the Enigma of Combination. The series features the character Windblade in a starring role despite the fact that she did not receive a toy in the Combiner Wars line (well, at least not a mass retail release; there was an extremely limited edition convention exclusive Windblade figure). Windblade was the product of a previous fan poll (similar to Victorion) and she was prominently featured in the IDW Transformers comics as an affable young Transformer from the planet Caminus trying to navigate her way around the intricacies of Cybertronian society.
In the Combiner Wars animated series, however, Windblade is a perpetually angry killer with a serious axe to grind against the combiners, the Autobots, and the Decepticons. Apparently, the combiners destroyed her home planet, although it's not clear why this happened or even how. It's not even clear what the Combiner Wars are about; are they wars between combiners or are they wars against combiners? It doesn't matter because the series only features one fight between two combiners. Windblade furiously kills Menasor, the Stunticon combiner, after he had previously defeated Computron, the Technobot combiner, in battle. Now here's my question: what makes the combiners such a threat if a normal-sized Transformer like Windblade can kill one in about 20 seconds? Also, it's not certain what the combiners are: the series treats them as if they're relatively new creations and that they are their own race of Transformers, but this is later contradicted when Starscream explicitly describes them all as Autobots and Decepticons and Megatron is seen trying to give orders to Devastator, the Constructicon combiner, like he's been doing it all his life.
It only gets more confusing from there. The Enigma of Combination is apparently this really powerful artifact that either controls or creates combiners. It is never stated how the ruling committee of Cybertron acquired it, where it came from, or what its actual function is. The main conflict of the series winds up being between the ruling council of Cybertron and an unlikely team of Optimus, Megatron, and Windblade, who all agree that the Enigma must be destroyed. But if it could control the combiners, why not just use it to make them stop fighting and smashing planets? The point is rendered moot when Starscream betrays the council (of course) and seizes the Enigma for himself to use its power to become the ultimate combiner. This involves him absorbing a couple of combiners and then turning into a giant screaming head. Huh?
Also, while the Camien characters would be familiar to readers of the IDW comic series, they are given no background whatsoever in this animated series, so a character named Mistress of Flame (who has no toy of any type) seems to just appear out of nowhere without any precedent in the series. (As it happens, Caminus was an ancient colony of Transformers who left Cybertron millions of years ago and who did not participate in the Autobot/Decepticon war, and the Mistress is a religious leader.) Also left unexplained is why the combiners continue fighting when everyone else has stopped.
Some of the stylistic choices in the series are puzzling as well. In addition to prominently featuring two characters without toys in the Combiner Wars line, the series inexplicably does not make use of many of the other characters' new toy designs. Glaringly, this applies to 3 of the 6 lead characters: Optimus, Megatron, and Rodimus. Starscream is the only main character whose animation model even somewhat resembles his new toy. Additionally, Victorion appears only briefly despite being heavily promoted as an integral character in the series. In fact, the only combiners who actually even appear are Menasor, Computron, Devastator, and Victorion, despite the fact that the toyline had like 10 of them for sale. Now, I understand that 40 minutes of content will limit the number of characters you can show, but it seems truly odd that the characters who represent the driving gimmick of the entire toyline are an afterthought. And it also makes one think "gee, maybe this isn't the best format to tell this story" because I still can't figure out what the fuck the story is.
From a production standpoint, there's no easy way to say this: it's terrible. Despite the fact that it was scripted by Westerners in the English language, the dialogue is written like it was translated from a Japanese anime and the acting features frequent anime-like grunts, screams, and "uuhhh??"s. There are frequent mismatches in tone between the actors, which I have personally always found annoying. And the animation itself is not great either. It's computer-animated, of course, and the characters' faces lack all but the most rudimentary emotive capabilities. For whatever reason, the show didn't even begin airing until after the Combiner Wars toyline had ended. I could go on, but I think you get the point.
At the very least, the toyline was reasonably successful. It ran from the end of 2014 until the summer of 2016. It was succeeded by Transformers: Titans Return, whose chief gimmick (or "play pattern," as it's euphemistically known) featured smaller robots transforming into the heads of larger robots, which was itself a reimagining of a type of 1980s Transformer called a Headmaster.