Is Purgatory legal in Standard, Modern, and Commander?

Purgatory is legal in: Legacy, Vintage, Commander.

What type of card is Purgatory?

Purgatory is an Enchantment. Its oracle text reads: "Whenever a nontoken creature is put into your graveyard from the battlefield, exile that card.At the beginning of your upkeep, you may pay {4} and 2 life. If you do, return a card exiled with Purgatory to the battlefield."

Purgatory

Enchantment

Whenever a nontoken creature is put into your graveyard from the battlefield, exile that card.<br>At the beginning of your upkeep, you may pay and 2 life. If you do, return a card exiled with Purgatory to the battlefield.