In Slay the Spire 2, co-op gameplay allows one player to host a multiplayer save, with up to three additional players joining as long as they are Steam friends. There are no password-protected lobbies or matchmaking queues. Players must select a save profile with an unlocked character and choose 'Multiplayer' from the main menu. Each player has three profiles, can only host one campaign at a time, and must be present from the beginning of the game. Multiplayer campaigns feature individual inventories, and enemy stats scale with party size. Energy is not shared among players, and loot is distributed individually. Ascension progression in multiplayer is separate from single-player achievements, and players must complete all three acts as a team to earn Ascension levels, which apply to all characters in multiplayer.