Countdown to Final Crisis (2007-2008) is perhaps one of the most baffling things to come out of DC Comics. It was meant as the leadup to what would have been the biggest events in the DCU, but ultimately, it fell short, not bearing any connection to the Final Crisis for which it was named. Trying to summarize it is a difficult task, as the plotline is essentially a very shaky patchwork of loosely connected plot threads. But someone has to try:The multiverse has gone wonky. The Monitors have come back into existence with the return of the parallel universes, and they foresee a "Great Disaster" — and one Monitor, consulting The Source, is told that Ray Palmer (currently in exile since the events of Identity Crisis) is the answer. From here, the script splits into a variety of plot threads:
The Trickster and Pied Piper go undercover to gather info on the other Rogues, and get framed for murder. They wind up in a situation not unlike "The Defiant Ones" save for a surplus of homophobic potshots and unpleasantry.
Holly Robinson and Harley Quinn end up in a women's shelter organized by Athena (actually Granny Goodness in disguise), who trains them as warriors without telling them why.
Karate Kid and Triplicate Girl end up stranded in the past because Karate Kid's infected with a strange virus; they try to find a cure...unsuccesfully. Both of them die.
The Monitors mull over whether or not they should intervene, before ultimately taking actions that are... morally questionable.
The plot threads often overlapped as the result of the search for Ray Palmer, with heroes of one thread waylaid by villains of another, which resulted in a lot of multi-sided battles and several assassination attempts before Darkseid (who is shown playing with superhero action figures at points), The Monitors, Monarch, and Superman-Prime start slaughtering characters en masse. Multiple other plot points were also introduced, but these were resolved in other titles, as well as multiple spin-offs.The series came under pretty strong fire, from the near Justice League: Cry for Justice-levels of excess to the awkward introduction of multiple plot points. A common complaint was that the comics did not make sense, with multiple plot threads leading more-or-less nowhere, and there was much objection to the portrayal of many of the characters.
Tropes associated with Countdown to Final Crisis:
Aborted Arc: Many plot points introduced as important are never mentioned again—including the series itself.
A God Am I: Superboy-Prime. Not necessarily a mature god, but still...
All There in the Manual: Much of the coherency of Countdown hinged upon a familiarity with the multiple tie-in titles. This contributed in part to its unpopularity.
Apocalypse How: Earth-15 gets a Class X. Earth-51 gets a Class X-4. Earth-51 version 2.0 gets a Class 4.
Big Damn Heroes: Jimmy Olsen gave us a rather impressive variant; When Ray Palmer crawls into his brain to give Jimmy control over his superpowers, allowing Jimmy to transform and rescue Superman, who had been exposed to a healthy dose of Kryptonite Jimmy by Darkseid.
Canon Discontinuity: A good portion of the whole mess was rendered noncanon within weeks of it's completion. Everything concerning Superman-Prime, for example, was tossed out of the window, with the character going from his role in the Sinestro Corps War directly into Final Crisis: Legion of 3 Worlds.
Character Filibuster: Solomon the Monitor spends half the series repeatedly hijacking the Monitors' conference with constant, doom-prophesying horror stories about Crisis on Infinite Earths, in order to convince the other Monitors that they have to kill Bob and stop his interdimensional joyride, justify his murder of Duela Dent, and get everyone to help him wipe out all the people who were originally from Earth-2 and the other Pre Crisis parallel universes.
Depending on the Artist: The fact that all the issues were drawn by different artists caused many, many abrupt shifts not just in character models, but in basic layout and props throughout particular arcs.
Later on, the Red Robin costume worn by Jason Todd on Earth-51 appeared in Robin and was adopted by Tim Drake.
Does This Remind You of Anything?: Mary Marvel taking a pole from Zatanna and saying "Ooh, no wonder you wanted to keep this for yourself!" with a look of ecstasy on her face.
Dropped a Bridge on Him: Many characters. Duela Dent, The Jokester, Triplicate Girl, Trickster, Karate Kid, the version of Batman who might have redeemed Jason Todd and three alternate-universe Earths.
Earth-Shattering Kaboom: Superboy-Prime becomes one of these during the miniseries. Having been displaced from his own universe, he tries to find his way back - repeatedly flying into a rage at the inferior copies of Earth he finds in the alternate universes and destroying them.
Idiot Ball: Passed about like a hot potato. Mary Marvel pulls off a Face-Heel Turn twice; Monitors Bob and Solomon's The Plan; and Renee Montoya's decision to release Trickster and Pied Piper, (both suspects in a murder investigation) upon Trickster's demonstration of their innocence (puppets were involved), even though they both aided in the murder of Bart Allen, The Question's reasoning for letting two potential criminals walk, ("The puppets convinced me.") and the future humans keeping an ill Karate Kid in the past where he won't infect them.
Multiversal Conqueror: Monarch, who gathered an army of supervillains from the whole multiverse to fight its protectors, the Monitors. At the same time one of the Monitors, Solomon, plotted with Darkseid to conquer the multiverse. It's hard to say which one was worse.
Never Trust a Trailer: DC promoted the series with the hint that Jimmy Olsen was going to be killed off by The Joker early on. They handed out buttons at conventions reading "Jimmy Olsen must die!" and even did a cover for Wizard showing Superman mourning a dead Jimmy, complete with grisly Joker Venom smile. Countdown #51 has The Joker holding Jimmy's press pass on the cover. And in that issue, Jimmy... interviews the Joker for a news story, and nothing much else happens.
Nice Job Breaking It, Hero: Nice job bringing along a deadly plague that destroys an entire universe, then leaving without trying to solve the problem, "heroes". Special mention goes to that universe's version of Hal Jordan. The plague would have been confined to Earth, if he hadn't had the genius idea to go out into space to warn other planets... without realizing he was already infected.
Series Continuity Error: Renee Montoya's first appearance, and many others. Also particularly blatant in an issue that ends with Trickster and Pied Piper falling out of a futuristic plane at sunset, while the very next issue begins with them falling out of a regular jet in daylight.
Shoot the Shaggy Dog: Several, but Trickster making gay jokes about Pied Piper through half the series with the implication that he will learn a lesson about homophobia due to his adventure, only to be randomly shot through the head in the middle of things probably takes the cake.
Will Karate Kid and Triplicate Girl manage to find the cure to his mysterious virus? Nope!
Super Hero Origin/Start of Darkness: Issues #37-27, #25-13, #11, and #6 feature origin stories of various heroes and villains as a backup feature. Issue #28 is notable in featuring two (one each for the Trickster and the Pied Piper).
Swarm of Rats: Una is eaten alive by a swarm of mutated rats, and shows her Determinator street cred by continuing to fight them long enough to pass on her flight ring to another character, who escapes.
Take That, Audience!: Superman-Prime is a pretty visible potshot, voicing common reader complaints about the series as though they were First-World problems.