Is Thorn Lieutenant legal in Standard, Modern, and Commander?

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

Thorn Lieutenant

Q: What type of card is Thorn Lieutenant?

Thorn Lieutenant is a Creature — Elf Warrior. Its oracle text reads: "Whenever this creature becomes the target of a spell or ability an opponent controls, create a 1/1 green Elf Warrior creature token. {5}{G}: This creature gets +4/+4 until end of turn. Power/Toughness: 2/3"