Compelling Deterrence

• WWizards of the Coast2025-01-24
  Official Ruling
  The card returned to its owner’s hand may be the card they discard. If it’s the only card in that player’s hand, it must be discarded if you control a Zombie.
• WWizards of the Coast2025-01-24
  Official Ruling
  Compelling Deterrence checks to see if you control a Zombie after the target nonland permanent is returned to its owner’s hand. For example, if you target the only Zombie you control with Compelling Deterrence, you won’t discard a card.
• WWizards of the Coast2025-01-24
  Official Ruling
  If the target nonland permanent is an illegal target as Compelling Deterrence tries to resolve, it won’t resolve and none of its effects will happen. No player will discard a card.

Rulings via Scryfall