Revenant

• WWizards of the Coast2020-11-10
  Official Ruling
  The ability that defines Revenant's power and toughness applies in all zones, not just the battlefield.
• WWizards of the Coast2020-11-10
  Official Ruling
  If Revenant is dealt lethal damage at the same time as another creature you control, both die at the same time. The other creature won't die in time to raise Revenant's toughness.
• WWizards of the Coast2020-11-10
  Official Ruling
  As long as Revenant is in your graveyard, its ability will count itself.

Rulings via Scryfall