Is Mindless Null legal in Standard, Modern, and Commander?

Mindless Null is legal in: Modern, Legacy, Vintage, Commander, Pauper.

Mindless Null

Q: What type of card is Mindless Null?

Mindless Null is a Creature — Zombie. Its oracle text reads: "This creature can't block unless you control a Vampire. *Only a bloodchief can create vampires. The rest sire nulls, who become mindless beasts in their former bodies.* Power/Toughness: 2/2"