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.
Revelation - Choose and shuffle a non-story asset you control into your deck and discard the top 3 cards of your deck. If a copy of that asset is discarded, take 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.
This is more of a question than a point but Solemn Vow explicitly says it is played under the control of another investigator. So plausibly I can target it with this card, shuffle it into my deck, draw it and play it under the control of same investigator who owns it. Also, unless I'm also running Solemn Vow in my own deck it's probably the best target...
Just a quick note for beginners: cards in your hand or discard pile are also controlled by you and can be chosen to satisfy the card condition. It doesn't have to be a card in play. (see page 16 in the reference guide)