Cleric Resurrection

[endeavor]

1. Bought the game yesterday 17th edition.

2. Got online and found the rules modifications for 19th edition.

3. Found a previous post on Cleric Resurrection that indicated that the player must declare X cards and then discard X cards from those drawn or already in hand.

Question: Since the number of cards in the discard pile is most often unknown, can the player just declare an extremely large number to guarantee that the entire discard pile is available to choose from or must the number X declared be within the range of cards in the discard pile? Does this ability work on both discard piles, i.e. when drawing from the Doors Pile or Treasures Piles?

I may be mistaken but this ability appears to be "broken". Is this the case?