Is Dreamstealer legal in Standard, Modern, and Commander?

Dreamstealer is legal in: Modern, Pioneer, Legacy, Vintage, Commander.

What type of card is Dreamstealer?

Dreamstealer is a Creature — Human Wizard. Its oracle text reads: "Menace Whenever this creature deals combat damage to a player, that player discards that many cards. Eternalize {4}{B}{B} ({4}{B}{B}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a 4/4 black Zombie Human Wizard with no mana cost. Eternalize only as a sorcery.)"

Dreamstealer

Creature — Human Wizard

$0.26 ↗20 similarCommander, Modern

Menace

Whenever this creature deals combat damage to a player, that player discards that many cards.

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 Wizard with no mana cost. Eternalize only as a sorcery.)