Spoiler Alert for Episode 12 of 'Harley Quinn'.

It's the penultimate episode of 'Harley Quinn', and the stakes have never been higher. Uncontrollable mutated plant monsters, an unhinged Jim Gordon (Chris Meloni) operating tanks, and even an appearance from the Justice League all come together in the biggest episode of Harley Quinn yet.

To quickly sum up: the tree monsters running amok in Gotham park turn out to be a distraction, only meant to lure in the Justice League so that the Queen of Fables (Wanda Sykes) can trap them in her book. The whole plan is revealed to have been orchestrated by the Joker (Alan Tudyk), who destroys the Legion of Doom headquarters in petty retaliation for having hired Harley Quinn (Kaley Cuoco).

Poison Ivy (Lake Bell) drinks some of the fertilizer that made the plants grow, increasing her size — which makes her a target. She's killed, and while it's not as surprising as some of the other deaths on the show, what really makes her death land is how seriously the show takes it. For a series that's built upon shock, violence, and humour, Ivy's death is a surprisingly chilling moment.

With Harley's crew completely reunited after the last episode, the jokes are a mile a minute. The episode abandons the supervillainy-as-a-career parody that it's been dependant on all season long, and plays out as a straight-up comedic superhero show.

Even Kite Man (Matt Oberg) gets to make a triumphant rescue, saving the day — with a kite. The appearance of the Justice League really drives home how out of hand things have gotten. It's a thrilling moment to see their appearance, though when they're seen from the side of the villains they're a little terrifying. The show is harsher on its superheroes than they would be treated on their own series, with the League prepared to throw Harley and crew into the Phantom Zone without so much as verifying guilt. Harley has apparently hit that villainess glass ceiling that demands immediate, over-the-top punishment.

It all culminates in one of the Joker's best entrances, as a giant tower with his face on it destroys L.O.D. H.Q., declaring his victory over Gotham City.

It's interesting that the dramatic reveal was an idea he stole from Harley Quinn. It's also fascinating that this entire plan was based on his enmity with her. He finally sees her as an equal, which is something she's been working on all season long, only because of his wounded pride, his mind equates "equal" to "threat". Alan Tudyk's Joker is defined by incredible heights of pettiness that's now taken to a new level, with the Joker sitting in a tower of hurt feelings. He doesn't admit to any of it but instead gloats in his victory.

The show goes all in on its stakes with the death of Harley Quinn. All humor ceases, as does the background noise. The show is suddenly quiet, empty, and haunting. It's a comic book TV series, and there's a number of ways Ivy can be brought to life, but none of that matters with how straight the show plays it. It's a hard-hitting moment, and Joker's gleeful laughter drives up his despicability effectively.

It's a blockbuster episode, leaving behind its commentary on career villainy, and letting the mile-a-minute gags grab the spotlight instead.

The quick jokes are some of the funniest, and wittiest of the season, and it's all so much fun that the cold, quiet, and oddly beautiful death of Poison Ivy makes the moment all the more haunting. The Joker as a villain has never been scary because of how big a threat he is, but because of how deeply he twists the knife, and in targeting Poison Ivy, he could not have twisted that knife any deeper if he'd taken out Harley herself. With one episode remaining, it's time for the Joker to get his final comeuppance.

The final episode of 'Harley Quinn' airs February 21, on DC Universe.