Is Siege Behemoth legal in Standard, Modern, and Commander?

Siege Behemoth is legal in: Legacy, Vintage, Commander.

Siege Behemoth

Q: What type of card is Siege Behemoth?

Siege Behemoth is a Creature — Beast. Its oracle text reads: "Hexproof As long as this creature is attacking, for each creature you control, you may have that creature assign its combat damage as though it weren't blocked."

Creature — Beast

Hexproof

As long as this creature is attacking, for each creature you control, you may have that creature assign its combat damage as though it weren't blocked.

Set Commander Anthology

Rarity Rare

Mana Value 7

Artist Jason A. Engle

Collector # 144

Scryfall Gatherer