Forbidding Spirit

• WWizards of the Coast2019-01-25
  Official Ruling
  While Forbidding Spirit’s effect is in effect, your opponents can choose not to pay to attack with a creature that attacks “if able.” If there’s no other player or planeswalker to attack, that creature simply doesn’t attack.
• WWizards of the Coast2019-01-25
  Official Ruling
  Because it doesn’t modify the characteristics of creatures, Forbidding Spirit’s triggered ability can affect creatures that enter the battlefield after that ability resolves.
• WWizards of the Coast2019-01-25
  Official Ruling
  In a Two-Headed Giant game, creatures can attack your teammate and planeswalkers your teammate controls without requiring a mana payment.
• WWizards of the Coast2019-01-25
  Official Ruling
  Forbidding Spirit’s effect continues until your next turn even if Forbidding Spirit leaves the battlefield before then.

Rulings via Scryfall