Is Headsplitter legal in Standard, Modern, and Commander?

Headsplitter is legal in: Modern, Legacy, Vintage, Commander, Pauper.

Headsplitter

Q: What type of card is Headsplitter?

Headsplitter is an Artifact — Equipment. Its oracle text reads: "When this Equipment enters, create a 1/1 black Assassin creature token with menace, then attach this Equipment to it. Equipped creature gets +1/+0. Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)"