Is Geistflame Reservoir legal in Standard, Modern, and Commander?

Geistflame Reservoir is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

What type of card is Geistflame Reservoir?

Geistflame Reservoir is an Artifact. Its oracle text reads: "Whenever you cast an instant or sorcery spell, put a charge counter on this artifact. {1}{R}, {T}, Remove any number of charge counters from this artifact: It deals that much damage to any target. {1}{R}, {T}: Exile the top card of your library. You may play that card this turn."