Is Durnan of the Yawning Portal legal in Standard, Modern, and Commander?

Durnan of the Yawning Portal is legal in: Legacy, Vintage, Commander.

Durnan of the Yawning Portal

Q: What type of card is Durnan of the Yawning Portal?

Durnan of the Yawning Portal is a Legendary Creature — Human Warrior. Its oracle text reads: "Whenever Durnan attacks, look at the top four cards of your library. You may exile a creature card from among them. Put the rest on the bottom of your library in any order. For as long as that card remains exiled, you may cast it. That spell has undaunted. (It costs {1} less to cast for each opponent.) Choose a Background (You can have a Background as a second commander.) Power/Toughness: 3/3"

Legendary Creature — Human Warrior

Whenever Durnan attacks, look at the top four cards of your library. You may exile a creature card from among them. Put the rest on the bottom of your library in any order. For as long as that card remains exiled, you may cast it. That spell has undaunted. (It costs less to cast for each opponent.)