Exclusive: LEGO Batman: Legacy of the Dark Knight Deluxe Edition - Mayhem Collection DLC Trailer Reveals The Joker and Harley Quinn Story Mission and More

During the gamescom Studio livestream, IGN exclusively revealed the trailer for LEGO Batman: Legacy of the Dark Knight Deluxe Edition - Mayhem Collection DLC, which features an exciting look at the new story mission starring Harley Quinn and The Joker, the Mayhem Mode, and the Sinister Pack.

LEGO Batman: Legacy of the Dark Knight's Mayhem Collection DLC will be available to all Deluxe Edition owners for no extra cost on September 18, 2026, which also happens to be the same day the game launches on Nintendo Switch 2.

The big addition in the DLC is that new story mission that stars Harley Quinn and The Joker, which will see the pair working together to "orchestrate a breakout from Arkham Asylum with a going-away party Gotham City won't soon forget."

Harley Quinn will be equipped with her trusty hammer and her Fun Gun loaded with Confetti and Bubblegum, and she'll also be able to summon her beloved hyenas, Bud & Lou. As for The Joker, he'll bring his Paintball Pelter and Boxing Glove to the party alongside a "fast-paced, agile combat style that is focused on speed and mobility." Players will also be able to unlock outfits for Harley Quinn and The Joker that are based on past Batman Media, including The Dark Knight Returns comic book series, Batman: The Animated Series, and more.

Details

Outside of the story, the Mayhem Mode will unleash Harley Quinn and The Joker across Gotham City and task them with time-limited Mayhem Runs. During each run, they will need to make it back to Amusement Mile before time runs out, and they will be chased by Batman and Robin while doing so. You'll earn LEGO studs by smashing everything in sight and completing challenges, alongside battling A.R.G.U.S. Agents and members of Amanda Waller's Task Force X in Deathstroke, Killer Croc, Captain Boomerang, Deadshot, King Shark, Polka-Dot Man, and other "notorious DC Super-Villains."

The Sinister Pack includes themed outfits inspired by popular DC comic book issues and action figures, plus a new vehicle and Batcave customization options. The full list of items this pack includes is as follows:

• Batman – The Batman Who Laughs outfit (Dark Nights: Metal #2 | 2017)
• Robin – Robin King outfit (Dark Nights: DM – Legends of the Dark Knights #1 | 2020)
• Nightwing – Joker outfit (Nightwing #16 | 2011)
• Batgirl – Joker outfit (Jokerized DC Multiverse Action Figure)
• Jim Gordon – Joker outfit (The Joker: The Man Who Stopped Laughing #9 | 2022)
• Catwoman – Joker outfit (Catwoman #65 | 1993)
• Talia al Ghul – Joker (Earth-37) outfit (DC Elseworlds comic series | 1997)
• Vehicle – Jokermobile (Arkham Trilogy)
• Batcave Items – Helmet (The Merciless), Joker Fish Aquarium, Barbatos Statue, Snake Clowns, and Long Halloween Pumpkin

The last thing that will be added on September 18 will be an enhanced 'Absolute' difficulty level, which will actually be a free update for all players. This new difficulty mode will require "greater skill, awareness, and precision in combat."

LEGO Batman: Legacy of the Dark Knight released on PS5, Xbox Series X/S, and PC back in May 2026, and in our review, we said, "a strong open-world Gotham and trademark Lego slapstick humour powers a fantastic plastic parody of Batman’s greatest hits."

For more, check out everything announced from Opening Night Live and what else to expect from the rest of gamescom.

Adam Bankhurst is a writer for IGN. You can follow him on X/Twitter @AdamBankhurst, Instagram, and TikTok, and listen to his show, Talking Disney Magic.