Is Natural Unity legal in Standard, Modern, and Commander?

Natural Unity is legal in: no major formats. It is banned in: Legacy, Vintage, Commander, Pauper.

Natural Unity

Q: What type of card is Natural Unity?

Natural Unity is a Conspiracy. Its oracle text reads: "Hidden agenda (Start the game with this conspiracy face down in the command zone and secretly choose a card name. You may turn this conspiracy face up any time and reveal that name.) Creatures you control with the chosen name have "At the beginning of combat on your turn, you may pay {G}. If you do, put a +1/+1 counter on this creature.""

Conspiracy

Hidden agenda (Start the game with this conspiracy face down in the command zone and secretly choose a card name. You may turn this conspiracy face up any time and reveal that name.)

Creatures you control with the chosen name have "At the beginning of combat on your turn, you may pay . If you do, put a +1/+1 counter on this creature."