The DarkLands cooperative expansion requires two Adventure Time Card Wars decks to play. Players join forces against DarkLands Creatures and a powerful Overlord armed with devastating Curses. The Army deck contains 4 factions to mix and match to create sinister pairings. To win, defeat the Overlord before your castle is overrun or either you or your partner fall!

Contents include 4 DarkLands Overlords to defeat, 4 DarkLands Landscapes, and 91 cards (44 Creature, 40 Curse, 5 Barrier, 2 Difficulty Reminder), plus various tokens.

The DarkLands expansion was first released in a 2025 Kickstarter stretch goals box with other Card Wars cards. That version included 5 Overlords, 4 Landscapes, and 108 cards.