Is Dreadhound legal in Standard, Modern, and Commander?

Dreadhound is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Dreadhound

Q: What type of card is Dreadhound?

Dreadhound is a Creature — Demon Dog. Its oracle text reads: "When Dreadhound enters, mill three cards. (Put the top three cards of your library into your graveyard.)Whenever a creature dies or a creature card is put into a graveyard from a library, each opponent loses 1 life."

Creature — Demon Dog

When Dreadhound enters, mill three cards. (Put the top three cards of your library into your graveyard.)<br>Whenever a creature dies or a creature card is put into a graveyard from a library, each opponent loses 1 life.

Set Pioneer Masters

Rarity Uncommon

Artist Joe Slucher