Is Counterflux legal in Standard, Modern, and Commander?

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

What type of card is Counterflux?

Counterflux is an Instant. Its oracle text reads: "This spell can't be countered.Counter target spell you don't control.Overload {1}{U}{U}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")"

Counterflux

Instant

This spell can't be countered.<br>Counter target spell you don't control.<br>Overload (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")