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.
Revelación - Elige un Apoyo que controles que no sea de historia, añádelo a tu mazo y baraja éste. Descarta las 3 primeras cartas de tu mazo. Si es descartada una copia de ese Apoyo, recibe 2 puntos de 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.