LEGO Batman: Legacy of the Dark Knight’s Mayhem Collection has received its first full gameplay-focused trailer. Joker, Harley Quinn, Mayhem Mode and the Sinister Pack had already been announced, but the Gamescom footage and developer details now explain how the new systems actually work.

The DLC launches on September 18, 2026. It is included with the Deluxe Edition, while owners of the Standard Edition will be able to upgrade separately.

Mayhem Runs turn Gotham into a timed escape

The centerpiece is Mayhem Mode. Joker and Harley take on timed Mayhem Runs that send them across Gotham to smash targets, wreck vehicles and shops, collect studs and complete objectives before the clock runs out.

The goal is not just destruction. Players must make it back to Amusement Mile in time while Batman and Robin actively pursue them, turning the open city into a more focused chase-and-escape mode.

Joker and Harley play differently

The new footage makes it clear that the two villains are not simple Batman reskins. Joker uses gadgets including the Paintball Pelter and a spring-loaded Boxing Glove.

Harley Quinn gets her own toolkit, including the Confetti Fun Gun and Bubble Gum Gun, and she is accompanied by her hyenas Bud and Lou.

The Crew System adds recruitable Arkham inmates

One of the more distinctive additions is the new Crew System. Joker and Harley can recruit inmates from Arkham and bring them along as helpers.

Those recruits can assist in combat, help break into shops and contribute to objectives, giving Mayhem Mode a small squad-management layer rather than reducing it to pure destruction.

Task Force X adds a rotating threat

Batman and Robin are not the only characters hunting the player. Task Force X can also appear, with its lineup changing between runs.

Confirmed members include Deathstroke, Killer Croc, Captain Boomerang, Deadshot, King Shark and Polka-Dot Man. That rotating roster should make repeated attempts feel less predictable.

The story mission begins with an Arkham breakout

The DLC also includes a new story mission built around Joker and Harley staging a breakout from Arkham Asylum before taking their chaos into Gotham.

That setup provides the narrative bridge into the new Mayhem systems, recruitable inmates and the broader pursuit structure across the city.

The Sinister Pack adds outfits, the Jokermobile and Batcave items

The Sinister Pack is also part of the Mayhem Collection. It includes seven outfits, the Jokermobile and five additional Batcave elements.

Confirmed examples include The Batman Who Laughs outfit for Batman, Robin King, the Joker Fish Aquarium and the Barbatos Statue.

Absolute difficulty is free for all players

A new Absolute difficulty setting also arrives on September 18. Importantly, it is not locked behind the Mayhem Collection.

It will be released as a free update for all owners of the base game.

September 18 is the key date

Mayhem Collection launches on September 18, 2026. The Nintendo Switch 2 version of LEGO Batman: Legacy of the Dark Knight also arrives on the same day.

The real news from the latest reveal is therefore not simply that Joker and Harley are playable, but how their mode is structured: timed Mayhem Runs, dedicated gadgets, the Crew System and Task Force X now give the DLC a much clearer gameplay identity.