This card says: search the top 5 cards of the encounter deck for an enemy and put it into play engaged with you. Then reveal one less encounter card this phase. Shuffle the deck.
So- my reading is that I don't shuffle the deck until after revealing the cards. Therefore it's a primitive form of scrying; I can tell (for example) whether to use Eleanor on a treachery as I'll know if the replacement card is worse; or how many treacheries are coming so as not to waste A Test of Will on the wrong one.
Am I interpreting this correctly? The shuffle doesn't have a timing but it reads like it happens last.