Is Transforming Flourish legal in Standard, Modern, and Commander?

Transforming Flourish is legal in: Legacy, Vintage, Commander.

Transforming Flourish

Q: What type of card is Transforming Flourish?

Transforming Flourish is an Instant. Its oracle text reads: "Demonstrate (When you cast this spell, you may copy it. If you do, choose an opponent to also copy it. Players may choose new targets for their copies.) Destroy target artifact or creature you don't control. If that permanent is destroyed this way, its controller exiles cards from the top of their library until they exile a nonland card, then they may cast that card without paying its mana cost."

Instant

Demonstrate (When you cast this spell, you may copy it. If you do, choose an opponent to also copy it. Players may choose new targets for their copies.)

Destroy target artifact or creature you don't control. If that permanent is destroyed this way, its controller exiles cards from the top of their library until they exile a nonland card, then they may cast that card without paying its mana cost.

Set Tarkir: Dragonstorm Commander

Rarity Rare

Mana Value 3

Artist Xavier Ribeiro

Collector # 39

Scryfall Gatherer