Shadow of Doubt

If an effect says "You may search your library . . . If you do, shuffle your library" or "You may search your library . . . then shuffle your library," you can't choose to search, so you won't shuffle.

If an effect says "Search your library . . . then shuffle your library," you shuffle you libraries even though you can't search.

Effects that instruct you to reveal or look at cards from the top of you library will still work. Only effects that use the word "search" are affected.