Is Acolyte of Bahamut legal in Standard, Modern, and Commander?

Acolyte of Bahamut is legal in: Legacy, Vintage, Commander.

What type of card is Acolyte of Bahamut?

Acolyte of Bahamut is a Legendary Enchantment — Background. Its oracle text reads: "Commander creatures you own have "The first Dragon spell you cast each turn costs {2} less to cast." *You were on a wayward path until Bahamut showed you that power and kindness can unite beneath the same banner.*"