By now Arrowverse fans know what to expect whenever one of these shows reaches its 100th episode. Like Arrow's "Invasion!" and The Flash's "What's Past Is Prologue" before it, Supergirl marks this important milestone by bending the laws of time and space and allowing Kara Danvers to revisit some of the most pivotal moments from her costumed career. This may be the third time we've seen this formula in the Arrowverse, but "It's a Super Life" proves just how much water there is in this particular well.
One big thing working in Supergirl's favor is that the "time travel clip show" conceit fits a lot more organically into the show's ongoing narrative than it did with Arrow or The Flash. Arrow's 100th episode is great, mind you, but it had to juggle the warring needs of celebrating a milestone and acting as part of the Invasion crossover. Meanwhile, The Flash's 100th episode suffered from the same flaw as nearly every other Season 5 installment - the ill-conceived Cicada storyline poisoned everything it touched.

By comparison, Supergirl has no crossover to worry about, nor is it experiencing the same Season 5 woes as The Flash. Plus, it certainly doesn't hurt having fifth dimensional imp Mr. Mxyzptlk as a plot catalyst. That gives the writers carte blanche to do basically whatever they want.
Supergirl: "It's a Super Life" Photos

The real key to this episode's success, though, is the fact that it hinges on the absolute best Season 5 plot point - the collapse of Kara and Lena's friendship. The series spent years building up that friendship, only to have a vindictive Lex tear it all down with his dying breaths and turn Lena against her best friend. What would Kara do to take it all back? How much will she sacrifice to get a second chance at being honest with Lena?

Those questions form the emotional core of this episode. Again, because Supergirl spent so much time and effort cementing that friendship, it's easy to sympathize with Kara's desire to restore what was lost, even as she threatens to throw the entire Arrowverse timeline off-balance. Though there's little hope of anything actually changing by the end, we want to see Kara succeed all the same. Kara experiences a very full and cohesive arc over the course of this episode, realizing that everything had to happen the way that it did, and at some point she has to simply allow Lena to choose her own fate. All of this further highlights the idea that Season 5 will culminate in the all-important question - will Lena ultimately do what's right, or will her inner Luthor win out?

Along the way, we're treated to several alternate takes on what might have happened if Kara had attempted to reveal her secret sooner, with Lena's reactions ranging from anger to confusion to complete indifference depending on the circumstances. More than just an interesting look at what might have been, these scenes allow Katie McGrath to explore different sides of her character and refocus on her humanity in a season that's pushed her into darker and darker territory. The story cleverly uses the show's long and complex history top its advantage, showing how each identity reveal would have ultimately resulted in disaster for Kara and her friends. Maybe the script strains credulity by having a untied Kara/Lena alliance cause a domino effect that ends with Ben Lockwood murdering the show's entire supporting, but there's also the question of how much of this was exaggerated by Mxyzptlk for Kara's benefit.



Speaking of Mxyzptlk, Thomas Lennon makes a strong impression as he takes over a role previously played by Peter Gadiot way back in Season 2. Whatever motivated that casting change, Lennon really suits this more laid back, less antagonistic version of Mxy. Lennon brings the right mixture of charm, sadness and whimsy to the role, painting Mxy as a being motivated by equal parts boredom, regret and genuine fascination with three-dimensional existence. This episode plays like an homage to all those Star Trek: The Next Generation episodes built around the rivalry between Captain Picard and Q. And while I'd hate to see Supergirl recycle the Kara/Mxy pairing as often as TNG did with Picard and Q, it would be nice to see Lennon pop by and reprise the role once in a while.

It should also be mentioned that this episode makes strong use of several returning cast members. We get to see Jeremy Jordan's Winn's and Chris Wood's Mon-El back in action, along with old villains like Odette Annable's Reign and Sam Witwer as the aforementioned Ben Lockwood. These guest roles fit neatly into the flashback premise and help make the 100th episode milestone feel that much more special. Even if you've fallen behind on the series of late, it's worth popping in just to celebrate with these old friends.

Verdict

Supergirl relies on a tried-and-true method of celebrating its 100 episode. "It's a Super Life" is a heartfelt look back at the series' five-year run and the all-important relationship between Kara and Lena. It's often funny, but also a very downbeat and emotional examination of why this friendship could never have endured. Combine that strong emotional anchor with a wide cast of returning favorites, and this is definitely the anniversary celebration the series deserves.