Aven Mindcensor

For effects that check whether a player searched a library or may search a library, searching the top four cards of that library counts as searching that library.

After the search is complete, the entire library is shuffled.

Each search works exactly the same as normal except that the opponent doing the searching sees only the top four cards of that library. They can't look at the other cards in that library at all. Cards not in the top four cards of the library can't be found in the search, even if they're identifiable in some manner.

If an effect uses the word "search" once but allows an opponent to search for multiple cards, the top four cards remain the same throughout the entire search. Finding one card won't cause the fifth card to become included in the search.