X Clarification: If 1 or more cards are forcibly removed from an investigator’s deck and returned to the collection (such as when a card is exiled, or when a campaign effect forces an investigator to remove cards from their deck), that investigator must purchase cards so that a legal deck size is maintained. When purchasing cards in this manner, that investigator may purchase level 0 cards at 0 experience cost until a legal deck size is reached.
X This rule also applies if an effect alters an investigator’s deck size, deckbuilding restrictions, or deckbuilding options such that 1 or more cards must be removed from or added to their deck as a result. - FAQ, v.1.7, March 2020