Is Warden of the First Tree legal in Standard, Modern, and Commander?

Warden of the First Tree is legal in: Modern, Pioneer, Legacy, Vintage, Commander.

What type of card is Warden of the First Tree?

Warden of the First Tree is a Creature — Human. Its oracle text reads: "{1}{W/B}: This creature becomes a Human Warrior with base power and toughness 3/3. {2}{W/B}{W/B}: If this creature is a Warrior, it becomes a Human Spirit Warrior with trample and lifelink. {3}{W/B}{W/B}{W/B}: If this creature is a Spirit, put five +1/+1 counters on it. Power/Toughness: 1/1"