Kaito followed the clues his sister gave him, only to find his friend dead at the hands of a monster.

Shadow of Doubt

({U/B} can be paid with either {U} or {B}.)
Players can't search libraries this turn.
Draw a card.

Secret Lair Drop

Ravnica: City of Guilds

({UB} can be paid with either {U} or {B}.)
Players can't search libraries this turn.
Draw a card.

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.

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

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.