Frostfire Regalia

Frostfire Regalia is the tier 3 mage set.

Source
Most tier 3 items could be acquired through quests given by Archmage Angela Dosantos, who was found at Light's Hope Chapel in the Eastern Plaguelands. Before the quests became active, Echoes of War had to be completed.

The quests required several crafting materials, s (which dropped from Trash Mobs in Naxxramas) as well as a token from a boss in Naxxramas.

The only exception was the, which dropped directly from Kel'Thuzad in Naxxramas.

The set was removed, but it has since been reintroduced and made available from the Black Market Auction House (with the exception of the ring), where the starting bid for each piece is.