Witness the Future
Innistrad: Crimson Vow — Uncommon
Sorcery
Witness the Future rulings:
2021-11-19: If you choose zero target cards or the cards are illegal targets as Witness the Future resolves, the target player will still shuffle their library.
2021-11-19: If the player is an illegal target as Witness the Future resolves, the library won't be shuffled and any targeted cards remain in the graveyard.