Is Mirran Mettle legal in Standard, Modern, and Commander?

Mirran Mettle is legal in: Modern, Legacy, Vintage, Commander, Pauper.

Mirran Mettle

Q: What type of card is Mirran Mettle?

Mirran Mettle is an Instant. Its oracle text reads: "Target creature gets +2/+2 until end of turn. Metalcraft — That creature gets +4/+4 until end of turn instead if you control three or more artifacts. *"Our land will not yield to Phyrexian corruption!"*"