Many things let you look at cards in location decks before you encounter them, from Ezren or Harsk's powers to spells like Magic Eye. This can be a tremendous help as you race the hourglass.
Finding the villain early can mean the difference between success and failure. A spell like Clairvoyance can drive a villain to the top of a deck, leaving it waiting for you to return while you loot and lock down other locations.
Of course, all that pecking ahead comes at an opportunity cost: you could replace Clairvoyance in your deck with a spell that helps you defeat banes and acquire boons. Finding that monster is all well and good, but someone has to be able to beat it.
Looking ahead can also be dangerous. Cards that have the Trigger trait have powers that activate when you examine them. You can find yourself suddenly being bitten by a Termite Swarm or jumped by a Warband because you peeked ahead.