+1 for Corbon.
When we play we usually put dungeon cards in the graveyard to ensure we get no repeats in a single campaign, but that's not actually what the rules say. I believe it is theoretically possible for us to run out of dungeon cards playing this way, in which case we'd have to pull them all out and start again, but that hasn't happened to us as yet.
We play this way too - BUT - we also have been discarding the encounter and location cards as well. OBVIOUSLY, when we run out of certain encounter cards - we will pull them out and mix them back in - BUT - we want to get through and experience all the content we can - without the doubling of dungeons/locations/encounters... until we have to at least.
Thanks. We put the dungeon cards and encoutner and location cards in the graveyard. I was curious of this was a rule or not. We will continue to do so to allow us to play all the cards and not repeat.