Is Scourge of the Throne legal in Standard, Modern, and Commander?

Scourge of the Throne is legal in: Legacy, Vintage, Commander.

Scourge of the Throne

Q: What type of card is Scourge of the Throne?

Scourge of the Throne is a Creature — Dragon. Its oracle text reads: "Flying Dethrone (Whenever this creature attacks the player with the most life or tied for most life, put a +1/+1 counter on it.) Whenever this creature attacks for the first time each turn, if it's attacking the player with the most life or tied for most life, untap all attacking creatures. After this phase, there is an additional combat phase. Power/Toughness: 5/5"

Creature — Dragon

Flying

Dethrone (Whenever this creature attacks the player with the most life or tied for most life, put a +1/+1 counter on it.)

Whenever this creature attacks for the first time each turn, if it's attacking the player with the most life or tied for most life, untap all attacking creatures. After this phase, there is an additional combat phase.

Power/Toughness: 5/5

Set Tarkir: Dragonstorm Commander

Rarity Rare

Mana Value 6

Artist Michael Komarck

Collector # 230

Scryfall