Is Tainted Observer legal in Standard, Modern, and Commander?

Tainted Observer is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Tainted Observer

Q: What type of card is Tainted Observer?

Tainted Observer is a Creature — Phyrexian Bird. Its oracle text reads: "Flying Toxic 1 (Players dealt combat damage by this creature also get a poison counter.) Whenever another creature you control enters, you may pay {2}. If you do, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.) Power/Toughness: 2/3"

Creature — Phyrexian Bird

Flying

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)

Whenever another creature you control enters, you may pay . If you do, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)