To expound for those who have not played Disney Lorcana Illumineers Quest (hitherto referred as DLIQ) or similar types of games, I will give a rough framework for the idea. Please note that this is by no means a final product and would require a group of smart people to create (with minor input from me).
1.) Players bring their own decks with existing Redemption cards. The decks (maybe) only include heroes with appropriate enhancements, dominants, artifacts and fortresses. Decks would also include Lost Souls.
2.) The Antagonist Deck would be pre-constructed and include evil characters, enhancements, dominants and artifacts. These cards would be marked somehow so as not be used in normal tournament play. This is because they would be considerably stronger than normal to provide a challenge for multiple teamwork players.
3.) There would be a difficulty level indicator/card that would add buffs for the Antagonist's cards. For example: Level 1 - Cards remain as written. Level 2 - All cards gain cannot be interrupted. Level 3 - All cards cannot be protected against. Level 4 - All cards cannot be negated or protected against.
4.) There would be a designated prison camp where all defeated/discarded heroes and Lost Souls go to throughout the game. This would represent the losing condition for the players. If 30 cards are in prison then it is game over.
5.) Players would be rescuing Lost Souls, which are placed in a common area when drawn. Any player can rescue any Lost Soul by defeating the Antagonists' evil characters. The winning condition for the players is when EACH player has rescued a preset number of LSs. There is not a running total for the group (to avoid one player taking over the game).
6.) Any player cards that target an "opponent" always target the Antagonist. Antagonist cards that target a singular hero/player, the hero/player is chosen by the group. Some cards will target "all players" or "all heroes."
7.) The design of the Antagonist deck will encourage players to think outside the box and maybe use cards that are not used as often. The deck will have powerful and destructive cards. This is a staple for cooperative games in order to offset the combined power of the players. The players will usually need to work and strategize together in order to win.
**This is all subject to change and improvement. I just wanted to give the gist of the idea.**