Is Thunderstaff legal in Standard, Modern, and Commander?

Thunderstaff is legal in: Modern, Legacy, Vintage, Commander.

What type of card is Thunderstaff?

Thunderstaff is an Artifact. Its oracle text reads: "As long as this artifact is untapped, if a creature would deal combat damage to you, prevent 1 of that damage. {2}, {T}: Attacking creatures get +1/+0 until end of turn. *Jort the Thunder-Mad spent his life perfecting a way to harness the power of the heavens.*"