I picked up a second set really cheap
Now I know I can not add my extra heroes or Gandalf, but the other cards I can add to my deck.
But what cards can/should I add to the enemy deck??
Actually you can add Gandalf so with 2 core you can have 2 decks with 3 Gandalf cards each. Get 3 cores like I just did recently (I wanted some of the single cards at 3 copies and it was cheap} and you can have all 4 players with 3 Gandalf cards each.