Anticognition

• WOTC Official Reminder Textofficial rules
  Scry — Look at the top N cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.

• WWizards of the Coast2020-09-25
  Official Ruling
  Anticognition will counter the spell and let you scry 2 if any opponent has eight or more cards in their graveyard, not just that spell’s controller.
• WWizards of the Coast2020-09-25
  Official Ruling
  In a multiplayer game, once an opponent leaves the game, they won’t be considered for such an effect, no matter how many cards they had in their graveyard before leaving the game.
• WWizards of the Coast2020-09-25
  Official Ruling
  An ability that offers a bonus if an opponent has eight or more cards in their graveyard won’t provide additional benefits if more than one opponent has eight or more cards in their graveyard. There are also no additional benefits no matter how many cards are in an opponent’s graveyard, as long as there are at least eight.
• WWizards of the Coast2020-09-25
  Official Ruling
  Anticognition can target a spell that can’t be countered. You’ll still scry 2 if an opponent has eight or more cards in their graveyard.
• WWizards of the Coast2020-09-25
  Official Ruling
  If an opponent has eight or more cards in their graveyard, Anticognition can still target only a creature or planeswalker spell.

Rulings via Scryfall