Is Skanos Dragonheart legal in Standard, Modern, and Commander?

Skanos Dragonheart is legal in: Legacy, Vintage, Commander.

Skanos Dragonheart

Q: What type of card is Skanos Dragonheart?

Skanos Dragonheart is a Legendary Creature — Dragon Ranger. Its oracle text reads: "Whenever Skanos Dragonheart attacks, it gets +X/+X until end of turn, where X is the greatest power among other Dragons you control and Dragon cards in your graveyard. Choose a Background (You can have a Background as a second commander.) Power/Toughness: 4/4"

Legendary Creature — Dragon Ranger

Whenever Skanos Dragonheart attacks, it gets +X/+X until end of turn, where X is the greatest power among other Dragons you control and Dragon cards in your graveyard.

Choose a Background (You can have a Background as a second commander.)

Power/Toughness: 4/4

Set Commander Legends: Battle for Baldur's Gate

Rarity Uncommon

Mana Value 5

Artist Daarken

Collector # 255

Scryfall