Loaming Shaman

• WWizards of the Coast2019-07-12
  Official Ruling
  If Loaming Shaman’s triggered ability targets a player but doesn’t target any cards in that player’s graveyard, that player just shuffles their library.
• WWizards of the Coast2019-07-12
  Official Ruling
  If the target cards become illegal targets, the target player shuffles their library. If the target player becomes an illegal target, Loaming Shaman’s ability has no effect.

Rulings via Scryfall