In the Season 3 finale, Lex's insect half takes over completely, attacking League members and converting them to accomplices. The remaining heroes track Lex to a National Park, where she plans to start a conflagration that will destroy the entire planet.

Fearing that Lex's insectine influences have made The League a threat, Sgt. Agony imprisons the heroes beneath the mansion. As yet uncaptured, Black Saturn assembles a team to bust his roommates from their confinement. Lex remains on the run, fighting to contain her terrifying insect nature.

The insect traits Lex inherited from her mother, the evil Frau Mantiss, begin to take over her body, posing a threat to Storm City. Despite Rex's objections, Sgt. Agony orders both Leagues to bring Lex in, dead or alive. Robobot flees the city with a fugitive Lex to help her conquer her affliction.

Cooch and Liplor ride the success of their TV show while Saturn and Ranger join the crew. Titanium Rex and Dr. Devizo have unfinished business on an island where Sgt. Agony has identified a mysterious supervillian, whose powers combine with a tropical storm to render Devizo and Rex vulnerable.

Coming off the popularity of their boxing commentary, Cooch and Liplor get their big break appearing on a hit children's RV show. Robobot clumsily hides from Titanium Rex a secret...

When a Russian Super Soldier frozen in time thaws out and publicly challenges American Ranger to a boxing match, Ranger must confront his fears of letting down America.

The annual Thanksgiving turkey competition between Titanium Rex and Dr. Devizo goes awry when Rex's turkey transforms into a nightmarish bird monster whose eggs hatch additional freakish bird creatures at an alarming rate. Lex aims to prove herself worthy of a seat at the grown ups' table while Black Saturn brings The Groaner to his family's mansion for a traditional Wheelihan Thanksgiving dinner, complete with snobby gherkins and snobbier guests.

An old, powerful foe from Dr. Devizo's past returns to haunt him… and aims to kill him swiftly afterward. Both The League of Freedom and The League of Freedom West risk their lives keeping him alive while Lex struggles with an internal conflict over her genetic makeup.

The League of Freedom is enlisted for a top-secret mission on a perilous jungle island. Despite Cooch going feral and American Ranger succumbing to jungle paranoia, The League successfully identifies the island's supervillain. Elsewhere, Black Saturn desperately tries to prove himself a team leader.

Desperate for a comeback, Titanium Rex books an appearance for the team at a comic convention. In one of several humiliating experiences, he bumps into an old '90s version of The League, obsessed with pogs, roller blades and earning Rex's approval. Meanwhile, Lex is lured on a date.

When rival gangs of werewolves and vampires get caught in an eternal war that only Black Saturn can end, Courtney is inadvertently transformed into a vampire. Rex and Ranger are determined to steer Black Saturn away from the dark arts while Robobot steers Lex toward a mindful meditation practice.

The League of Freedom returns to their home timeline only to discover they've been replaced by the new "League of Freedom West." When Titanium Rex sees that the new squad includes an improved clone of himself, his insecurities get the best of him and his villainous proclivities emerge.

Under an evil spell, The League of Freedom is transported to an apocalyptic future where American Ranger rules the U.S. under a dictatorship. While the heroes confront the horrors that await them in this future, they must help Robobot and Future Robobot fix the time machine needed to return home.

The team heads to Hawaii where Titanium Rex (Bryan Cranston) runs into a vacationing former President Barack Obama (Jay Pharoah), Black Saturn (Tucker Gilmore) and Lex (Jillian Bell) teach Cooch (Heidi Gardner) how to swim, and American Ranger (Keegan-Michael Key) attempts to perform in a USO show while an evil threat brews under the sea.

To save former member Zenith, the League of Freedom travels to the Godsrealm to fight her evil Uncle Ridan; Robobot learns what it means to be a real boy as Rex must prove to be a hero true in order to wield the Sword of Azimuth.

When Cooch's claims that Leprechauns are attacking Storm City turn out to be true, the League of Freedom is drawn into a battle with assorted mythical creatures. The injured Black Saturn recruits Courtney to join the fight in a mechanized suit.

When the supervillains move out of the mansion and steal half the furniture, the League takes a trip to Swedish furniture store ILEGA; feeling stung by the Groaner's absence, Saturn finds a rebound nemesis in Bugula.

Claudette, Cooch's former owner, returns with a lawyer seeking to get her cat back, so Robobot agrees to represent Rex in the upcoming trial; the Groaner tries to discern the true meaning behind Black Saturn's name.

When Lex starts dating the vigilante anti-hero Max Penalizer, Titanium Rex and Dr. Devizo team up to break them up. As the villains of the mansion set their eyes on bedding Cooch, Robobot learns the dangers of telling humans little white lies.

After helping the League of Freedom save the world, Dr. Devizo and his team of villains move into the Mansion as bona fide heroes. The team struggles with their new roommates as Robobot travels across the country in search of the elusive Swine Kampf