Is Chromatic Armor legal in Standard, Modern, and Commander?

Chromatic Armor is legal in: Legacy, Vintage, Commander.

What type of card is Chromatic Armor?

Chromatic Armor is an Enchantment — Aura. Its oracle text reads: "Enchant creatureAs Chromatic Armor enters, choose a color.Chromatic Armor enters with a sleight counter on it.Prevent all damage that would be dealt to enchanted creature by sources of the last chosen color.{X}: Put a sleight counter on Chromatic Armor and choose a color. X is the number of sleight counters on Chromatic Armor."

Chromatic Armor

Enchantment — Aura

Enchant creature<br>As Chromatic Armor enters, choose a color.<br>Chromatic Armor enters with a sleight counter on it.<br>Prevent all damage that would be dealt to enchanted creature by sources of the last chosen color.<br>: Put a sleight counter on Chromatic Armor and choose a color. X is the number of sleight counters on Chromatic Armor.