Faceless Devourer

• WWizards of the Coast2021-03-19
  Official Ruling
  Auras attached to the exiled creature will be put into their owners' graveyards. Equipment attached to the exiled creature will become unattached and remain on the battlefield. Any counters on the exiled creature will cease to exist. Once the exiled creature returns, it's considered a new object with no relation to the object that it was.
• WWizards of the Coast2021-03-19
  Official Ruling
  If a token is exiled this way, it will cease to exist and won't return to the battlefield.
• WWizards of the Coast2021-03-19
  Official Ruling
  Three Faceless Devourers entering the battlefield at separate times with no other creatures with shadow on the battlefield will result in an infinite loop. The game ends in a draw unless a player somehow interrupts the loop.
• WWizards of the Coast2021-03-19
  Official Ruling
  If Faceless Devourer leaves the battlefield before its first triggered ability has resolved, its last ability triggers. This ability does nothing when it resolves. Then its first ability resolves and exiles the target creature indefinitely.
• WWizards of the Coast2021-03-19
  Official Ruling
  Once a creature has been blocked, that creature remains blocked and will deal and be dealt combat damage even if it gains or loses shadow or if the blocking creature gains or loses shadow.
• WWizards of the Coast2021-03-19
  Official Ruling
  If an attacking creature has multiple evasion abilities, such as shadow and flying, a creature can block it only if that creature satisfies all of the appropriate evasion abilities.
• WWizards of the Coast2021-03-19
  Official Ruling
  Multiple instances of shadow on the same creature are redundant.

Rulings via Scryfall