Is Necromaster Dragon legal in Standard, Modern, and Commander?

Necromaster Dragon is legal in: Modern, Pioneer, Legacy, Vintage, Commander.

Necromaster Dragon

Q: What type of card is Necromaster Dragon?

Necromaster Dragon is a Creature — Dragon. Its oracle text reads: "Flying Whenever this creature deals combat damage to a player, you may pay {2}. If you do, create a 2/2 black Zombie creature token and each opponent mills two cards."

Creature — Dragon

Flying

Whenever this creature deals combat damage to a player, you may pay . If you do, create a 2/2 black Zombie creature token and each opponent mills two cards.