Do cards with a cost of 0 require you to exhaust a Domain to play them?
I would have thought not, and indeed wouldn't even have asked the question, if not for the Sword Of Y'ha-tallo. Which, as I'm sure you're aware, has a printed cost of 0 but two Cthulhu faction symbols in front of it meaning, if I understand the rules correctly, that you must exhaust a Domain with at least two Cthulhu faction cards on it in order to bring the sword in to play despite its 0 cost ... ?