This WoW set features the full Valorous Terrorblade transmog, which is the rogue tier 8 (10-man) raid set. Terrorblade is obtained by looting tokens from Ulduar and trading those tokens in for set pieces via Dalaran tier vendors.
How to Get Rogue Tier 8? By slaying Wrath of the Lich King Ulduar bosses.
How Many Set Pieces?  Helmet, Shoulders, Chest, Hands, and Pants
Rogue Tier 8 Transmog: [10-Man Drop Locations]
Head: Helm of the Wayward Vanquisher [Mimiron ] in Ulduar.
Chest: Chestguard of the Wayward Vanquisher [Yogg-Saron] in Ulduar.
Hands: Gloves of the Wayward Vanquisher [Freya] in Ulduar.
Legs: Leggings of the Wayward Vanquisher [Hodir] in Ulduar.
Redeem Token Vendor: Valerie Langrom [51,72] in Dalaran.
Set Name: Valorous Terrorblade Battlegear (hover for set bonuses)
Shoulder: Valorous Terrorblade Pauldrons
Chest: Valorous Terrorblade Breastplate
Hands: Valorous Terrorblade Gauntlets
Legs: Valorous Terrorblade Legplates
Optional: Hands and Legs low droprate from [Emalon the Storm Watcher] in Vault of Archavon.