The text of this card is very missleading. As I encountered this one the first time without a single asset into my play area besides from permanents, it was kind of unclear to me, if I have to discard 3 cards or not. Since i cannot fulfill the "choose" part of the card, what to do next. The word "and" has no entry in the rulebook, so hard to say. In my opinion the cards wording should be: Revelation - Choose a non-story asset you control then shuffle it into your deck. Discard the top 3 cards of your deck. If a copy of that asset is discarded, take 2 horror.
Enthüllung - Wähle eine Nicht-Storyvorteilskarte, die du kontrollierst, mische sie in dein Deck und lege die obersten 3 Karten deines Decks ab. Falls eine Kopie dieser Vorteilskarte abgelegt wird, nimm 2 Horror.
This and Corrosion from Carcosa has made me appreciate throwaway assets like Cherished Keepsake and Leather Coat even more. It's very scary to only have must-have assets in play with this card in the encounter deck.