Null Chamber
Mirage — rare
World Enchantment
Null Chamber rulings:
2013-04-15: You choose which opponent makes the choice. Null Chamber does not target that opponent.
2008-10-01: This has the supertype world. When a world permanent enters the battlefield, any world permanents that were already on the battlefield are put into their owners’ graveyards. This is a state-based action called the “world rule.” The new world permanent stays on the battlefield. If two world permanents enter the battlefield at the same time, they’re both put into their owners’ graveyards.
2006-02-01: If you somehow manage to cast this while other spells are on the stack, those spells won’t be countered.