Historical Rules · 4 October 2019
Rule 701.19d
Official source text from the 4 October 2019 Rules release
If an effect would cause a player to shuffle a set of objects into a library, that library is shuffled even if there are no objects in that set. Example: Loaming Shaman says “When Loaming Shaman enters the battlefield, target player shuffles any number of target cards from their graveyard into their library.” It enters the battlefield, its ability triggers, and no cards are targeted. When the ability resolves, the targeted player will still have to shuffle their library.