Blood Curdle

• WWizards of the Coast2020-04-17
  Official Ruling
  Blood Curdle targets only one creature: the one that will be destroyed. You choose which creature to put a menace counter on after the target creature has been destroyed.
• WWizards of the Coast2020-04-17
  Official Ruling
  If a creature you control was exiled until the creature that was destroyed left the battlefield, the exiled creature returns in time to receive the counter.
• WWizards of the Coast2020-04-17
  Official Ruling
  If the target creature is an illegal target by the time Blood Curdle tries to resolve, the spell won’t resolve. You won’t put a menace counter on any creature. If the target is legal but not destroyed (most likely because it has indestructible), you do put a menace counter on a creature you control.

Rulings via Scryfall