From the announcement:
Asking for help is never a strong suit for villains, but sometimes they need a helping hand to snag a big score or take down a worthy hero. Villains like Captain Cold, Weather Wizard, Heatwave and the rest often need to work together to take down The Flash and his speedy allies. With DC Comics Deck-Building Game Crossover Pack 5: The Rogues, you become a Super-Villain who always has some help within reach, thanks to Teamwork.
“Teamwork” is a keyword found on each of the oversized Super-Villain cards and several new cards for the main deck. It allows you to play the top card of another player’s deck. The code “honor among thieves” usually applies here, as the player who you chose to assist you gets a piece of the action.