Is Observant Alseid legal in Standard, Modern, and Commander?

Observant Alseid is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Pauper.

Observant Alseid

Q: What type of card is Observant Alseid?

Observant Alseid is an Enchantment Creature — Nymph. Its oracle text reads: "Bestow {4}{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 to a creature.) Vigilance Enchanted creature gets +2/+2 and has vigilance. Power/Toughness: 2/2"

Enchantment Creature — Nymph

Bestow (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 to a creature.)