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Question about combining the expansions: Should the number of monsters always stay the same? Thus, how does it work if I put all the monsters from both expansions for the draw pile?The Monster cards from both games should NOT be shuffled together. Use Monsters from Welcome Back if you want to include Special Monsters, or Monsters from either game if you don't.
To combine both games, just use all the 8 Heroes in a game: this way, you have more options each round.