Is Mist Dancer legal in Standard, Modern, and Commander?

Mist Dancer is legal in: Legacy, Vintage, Commander.

Mist Dancer

Q: What type of card is Mist Dancer?

Mist Dancer is a Creature — Merfolk Wizard. Its oracle text reads: "Flying Other Merfolk you control get +1/+0 and have flying. Encore {5}{U}{U} ({5}{U}{U}, 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.)"

Creature — Merfolk Wizard

Flying

Other Merfolk you control get +1/+0 and have flying.

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.)