Is Fungus Elemental legal in Standard, Modern, and Commander?

Fungus Elemental is legal in: Legacy, Vintage, Commander.

Fungus Elemental

Q: What type of card is Fungus Elemental?

Fungus Elemental is a Creature — Fungus Elemental. Its oracle text reads: "{G}, Sacrifice a Forest: Put a +2/+2 counter on this creature. Activate only if this creature entered this turn. *I rot growth and grow rot. What am I? —Elvish riddle* Power/Toughness: 3/3"