Arkham Horror LCG: The Search for Kadath Exp.
Arkham Horror LCG: The Search for Kadath Exp. - Rules of Play says:
As your team of investigators becomes separated between the dream and the waking worlds, you will need to work together across realms to earn victory and return home. To help you achieve this, you will find new player cards that create new synergies between investigators, letting you offer aid during your turns or even the Mythos Phase. Discover the meaning behind your dreams and discover the proof you seek!