Is Soul of Eternity legal in Standard, Modern, and Commander?

Soul of Eternity is legal in: Legacy, Vintage, Commander.

Soul of Eternity

Q: What type of card is Soul of Eternity?

Soul of Eternity is a Creature — Avatar. Its oracle text reads: "Soul of Eternity's power and toughness are each equal to your life total. Encore {7}{W}{W} ({7}{W}{W}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.) Power/Toughness: */*"

Creature — Avatar

Soul of Eternity's power and toughness are each equal to your life total.

Encore (, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)