Is Ostrich-Horse legal in Standard, Modern, and Commander?

Ostrich-Horse is legal in: Standard, Modern, Pioneer, Legacy, Vintage, Commander, Pauper, Historic.

Ostrich-Horse

Q: What type of card is Ostrich-Horse?

Ostrich-Horse is a Creature — Bird Horse. Its oracle text reads: "When this creature enters, mill three cards. You may put a land card from among them into your hand. If you don't, put a +1/+1 counter on this creature. (To mill three cards, put the top three cards of your library into your graveyard.) *Ostrich-horses are renowned in the Earth Kingdom as reliable steeds for couriers, soldiers, and merchants.* Power/Toughness: 3/1"

Creature — Bird Horse

When this creature enters, mill three cards. You may put a land card from among them into your hand. If you don't, put a +1/+1 counter on this creature. (To mill three cards, put the top three cards of your library into your graveyard.)

*Ostrich-horses are renowned in the Earth Kingdom as reliable steeds for couriers, soldiers, and merchants.*

Power/Toughness: 3/1

Set Avatar: The Last Airbender

Rarity Common

Mana Value 3

Artist Pablo Rivera

Collector # 188

Scryfall