Purgatory

• WWizards of the Coast2004-10-04
  Official Ruling
  If destroyed at the same time some creatures are destroyed, the destroyed creatures are exiled and stay exiled.
• WWizards of the Coast2004-10-04
  Official Ruling
  If an opponent takes control of this card and pays for the upkeep ability, the creatures will enter under their control even if you exiled them.
• WWizards of the Coast2008-04-01
  Official Ruling
  This has been restored to a triggered ability that triggers when a nontoken creature is put into a graveyard from the battlefield, rather than a replacement effect. The creature does go to the graveyard, and will trigger any other abilities that look for this event.
• WWizards of the Coast2008-08-01
  Official Ruling
  If this card changes controllers between putting the upkeep triggered ability on the stack and resolving it, the creature is put onto the battlefield under the control of the player who controlled this card when the ability was put on the stack.

Rulings via Scryfall