Is Timeless Witness legal in Standard, Modern, and Commander?

Timeless Witness is legal in: Modern, Legacy, Vintage, Commander, Historic.

What type of card is Timeless Witness?

Timeless Witness is a Creature — Human Shaman. Its oracle text reads: "When this creature enters, return target card from your graveyard to your hand. Eternalize {5}{G}{G} ({5}{G}{G}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a 4/4 black Zombie Human Shaman with no mana cost. Eternalize only as a sorcery.)"

Timeless Witness

Creature — Human Shaman

When this creature enters, return target card from your graveyard to your hand.

Eternalize (, Exile this card from your graveyard: Create a token that's a copy of it, except it's a 4/4 black Zombie Human Shaman with no mana cost. Eternalize only as a sorcery.)