Is Helm of the Gods legal in Standard, Modern, and Commander?

Helm of the Gods is legal in: Modern, Pioneer, Legacy, Vintage, Commander.

What type of card is Helm of the Gods?

Helm of the Gods is an Artifact — Equipment. Its oracle text reads: "Equipped creature gets +1/+1 for each enchantment you control. Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.) *Its blessings are as numerous as the stars of Nyx.*"