Is Belonging legal in Standard, Modern, and Commander?

Belonging is legal in: Legacy, Vintage, Commander.

What type of card is Belonging?

Belonging is a Creature — Elemental Incarnation. Its oracle text reads: "When this creature enters, create three 1/1 colorless Shapeshifter creature tokens with changeling. (They're every creature type.) Encore {6}{W}{W} ({6}{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.)"

Belonging

Creature — Elemental Incarnation

When this creature enters, create three 1/1 colorless Shapeshifter creature tokens with changeling. (They're every creature type.)

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.)