X is the number of cards underneath Narrowing Gap.

When Revealed: Each player chooses 2 ready characters they control (objective allies not included). Each ready character that was not chosen is placed facedown underneath Narrowing Gap (attachments included, tokens are removed) and is considered to be out of play. This effect cannot be cancelled.

Response: When Narrowing Gap is explored as the active location, return each card underneath it to its owner's hand (heroes enter play immediately).