Is Undo legal in Standard, Modern, and Commander?

Undo is legal in: Legacy, Vintage, Commander, Pauper.

What type of card is Undo?

Undo is a Sorcery. Its oracle text reads: "Return two target creatures to their owners' hands."

Sorcery

Return two target creatures to their owners' hands.

Set Visions

Rarity Common

Artist Terese Nielsen

Sorcery Commander Pauper Legacy