Is Swarm Shambler legal in Standard, Modern, and Commander?

Swarm Shambler is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Swarm Shambler

Q: What type of card is Swarm Shambler?

Swarm Shambler is a Creature — Fungus Beast. Its oracle text reads: "This creature enters with a +1/+1 counter on it. Whenever a creature you control with a +1/+1 counter on it becomes the target of a spell an opponent controls, create a 1/1 green Insect creature token. {1}, {T}: Put a +1/+1 counter on this creature."

Creature — Fungus Beast

This creature enters with a +1/+1 counter on it.

Whenever a creature you control with a +1/+1 counter on it becomes the target of a spell an opponent controls, create a 1/1 green Insect creature token.

, : Put a +1/+1 counter on this creature.