Blot Out

• WWizards of the Coast2023-05-12
  Official Ruling
  Blot Out targets only the opponent, not any permanent. A permanent with hexproof may be exiled this way if its mana value is the greatest, for example.
• WWizards of the Coast2023-05-12
  Official Ruling
  Consider all creatures and planeswalkers the target opponent controls as one group to see which one has the greatest mana value. For example, if the opponent controls a creature with mana value 3 and a planeswalker with mana value 5, they must exile the planeswalker.
• WWizards of the Coast2023-05-12
  Official Ruling
  Which creature or planeswalker will be exiled is determined as Blot Out resolves.

Rulings via Scryfall