Is Nyxborn Shieldmate legal in Standard, Modern, and Commander?

Nyxborn Shieldmate is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Pauper.

Nyxborn Shieldmate

Q: What type of card is Nyxborn Shieldmate?

Nyxborn Shieldmate is an Enchantment Creature — Human Soldier. Its oracle text reads: "Bestow {2}{W} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached.) Enchanted creature gets +1/+2."