betrayal at house on the hill crystal ball and used items
Looking at the rules here there are instructions for discarding rooms tiles.


  If you go through the whole stack of room tiles, shuffle the tiles you set aside in a discard pile


With that in mind I would handle all discards (of room tiles cards etc) into a discard pile for each and shuffle again if the draw deck for them runs out.  I couldn't see anything in rules about discarding to bottom of deck so that doesn't feel correct.