Is Heralds of Tzeentch legal in Standard, Modern, and Commander?

Heralds of Tzeentch is legal in: Legacy, Vintage, Commander.

Heralds of Tzeentch

Q: What type of card is Heralds of Tzeentch?

Heralds of Tzeentch is a Creature — Demon. Its oracle text reads: "Flying Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)"

Creature — Demon

Flying

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Set Warhammer 40,000 Commander

Rarity Uncommon

Mana Value 5

Artist Games Workshop

Collector # 23

Scryfall Gatherer