Is Unstable Amulet legal in Standard, Modern, and Commander?

Unstable Amulet is legal in: Modern, Legacy, Vintage, Commander, Historic.

Unstable Amulet

Q: What type of card is Unstable Amulet?

Unstable Amulet is an Artifact. Its oracle text reads: "When this artifact enters, you get {E}{E} (two energy counters). Whenever you cast a spell from anywhere other than your hand, this artifact deals 1 damage to each opponent. {T}, Pay {E}{E}: Exile the top card of your library. You may play it until you exile another card with this artifact."