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

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

Angelic Observer

Q: What type of card is Angelic Observer?

Angelic Observer is a Creature — Angel Advisor. Its oracle text reads: "Affinity for Citizens (This spell costs {1} less to cast for each Citizen you control.) Flying *Still and solemn as the statues of her kind that decorated the Park Heights rooftops, she gazed in sorrow on the city below.* Power/Toughness: 3/3"