This WoW set features the full Frostfire Regalia transmog, which is the mage tier 3 raid set. Frostfire was orginally added in vanilla patch 1.11.0, then removed with the Naxxaramas revamp during Wrath of the Lich King, and finally made available once again in Mists of Pandaria via the Black Market Auction House.
How to get mage tier 3? By bidding for the pieces on the BMAH.
How many set pieces?  Helmet, Shoulders, Chest, Bracer, Hands, Belt, Pants, and Feet.
Mage Tier 3 Transmog:
Head: Frostfire Circlet by purchasing the helmet from the BMAH.
Chest: Frostfire Robe by purchasing the chest from the BMAH.
Wrist: Frostfire Bindings by purchasing the bracers from the BMAH.
Hands: Frostfire Gloves by purchasing the gloves from the BMAH.
Waist: Frostfire Belt by purchasing the belt from the BMAH.
Legs: Frostfire Leggings by purchasing the pants from the BMAH.
Feet: Frostfire Sandals by purchasing the boots from the BMAH.