Rule 701.20c

If an effect would cause a player to shuffle one or more specific objects into a library, that library is shuffled even if none of those objects are in the zone they’re expected to be in or an effect causes all of those objects to be moved to another zone or remain in their current zone. Example: Guile says, in part, “When Guile is put into a graveyard from anywhere, shuffle it into its owner’s library.” It’s put into a graveyard and its ability triggers, then a player exiles it from that graveyard in response. When the ability resolves, the library is shuffled. Example: Black Sun’s Zenith says, in part, “Shuffle Black Sun’s Zenith into its owner’s library.” Black Sun’s Zenith is in a graveyard, has gained flashback (due to Recoup, perhaps), and is cast from that graveyard. Black Sun’s Zenith will be exiled, and its owner’s library will be shuffled.

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