Is Mastery of the Unseen legal in Standard, Modern, and Commander?

Mastery of the Unseen is legal in: Modern, Pioneer, Legacy, Vintage, Commander.

What type of card is Mastery of the Unseen?

Mastery of the Unseen is an Enchantment. Its oracle text reads: "Whenever a permanent you control is turned face up, you gain 1 life for each creature you control. {3}{W}: Manifest the top card of your library. (Put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)"

Mastery of the Unseen

Enchantment

Whenever a permanent you control is turned face up, you gain 1 life for each creature you control.

: Manifest the top card of your library. (Put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)