This WoW set features the full Conqueror’s Terrorblade transmog, which is the rogue tier 8.5 (25-man) raid set. Terrorblade is obtained by looting tokens from Wrath of the Lich King bosses and purchasing some set pieces via Dalaran tier vendors with gold.
How to Get Rogue Tier 8.5? By purchasing from vendors and slaying Ulduar bosses.
How Many Set Pieces?  Helmet, Shoulders, Chest, Hands, and Pants
Rogue Tier 8.5 Transmog: [25-Man Drop Locations]
Head: Crown of the Wayward Vanquisher [Purchase from vendor] in Dalaran.
Chest: Breastplate of the Wayward Vanquisher [Purchase from vendor] in Dalaran.
Hands: INSERT [Gauntlets of the Wayward Vanquisher] in Ulduar.
Legs: INSERT [Legplates of the Wayward Vanquisher] in Ulduar.
Head/Chest Vendor (Alliance): Arcanist Ivrenne [37,55] in Dalaran.
Head/Chest Vendor (Horde): Magistrix Lambriesse [65,23] in Dalaran.
Redeem Token Vendor: Valerie Langrom [51,72] in Dalaran.
Set Name: Conqueror’s Terrorblade Battlegear (hover for set bonuses)
Shoulder: Conqueror’s Terrorblade Pauldrons
Chest: Conqueror’s Terrorblade Breastplate
Hands: Conqueror’s Terrorblade Gauntlets
Legs: Conqueror’s Terrorblade Legplates
Optional: Hands and Legs low droprate from [Emalon the Storm Watcher] in Vault of Archavon.