The Underworld
From Arkham Horror Wiki
List of other world encounters
Errata
Other: The way is shut, and more doors close with each passing eon. If there are four or more elder sign tokens in play, take this card. While you have it, during Upkeep, you must discard a Clue token or 1 Item, if you have either. (errata: the following was not printed in the English version, but was in the French and German versions) Put a Clue on that card for each Item or Clue you discarded. Put that card back in the box when there are 3 Clues on it.