Lego Batman: Legacy of the Dark Knight's Mayhem Collection adds Harley Quinn's Arkham Asylum look

Lego Batman: Legacy of the Dark Knight is getting its Mayhem Collection expansion on September 18, and GameSpot has an exclusive first look at one of Harley Quinn's unlockable outfits — her iconic costume from Rocksteady's Batman: Arkham Asylum. The expansion launches simultaneously on Switch 2, PC, PS5, and Xbox Series X|S.

The Arkham Asylum outfit trades Harley's classic jester spandex for a doctor-themed look with a leather corset, domino mask, and repurposed medical attire — a dramatic redesign that debuted in the 2009 game. In Lego Batman: Legacy of the Dark Knight, the costume is described as featuring prankster pigtails and a "chaotic" corset. Harley and the Joker co-headline the Mayhem Collection, and both characters come with multiple unlockable outfits across their new playable campaign.

TT Games describes the Mayhem Collection as a love letter to Batman: The Animated Series — the landmark '90s show that first introduced Harley Quinn as the Joker's sidekick. The expansion's new story mission covers the first meeting between Joker and Dr. Harleen Quinzel, back before she became Harley Quinn. There's also a tribute to Arleen Sorkin, Harley's original voice actor who passed away in 2023, alongside Easter eggs referencing other Batman films, games, comics, and TV shows.

The Mayhem Collection drops September 18. For anyone who picked up Lego Batman: Legacy of the Dark Knight — one of the standout games of 2026 — this looks like a meaty reason to return to Gotham, or rather, to burn it down.