This WoW set features the full Valorous Cryptstalker transmog, which is the hunter tier 8 (10-man) raid set. Cryptstalker is obtained by looting tokens from Ulduar and trading those tokens in for set pieces via Dalaran tier vendors.
How to Get Hunter Tier 8? By slaying Wrath of the Lich King Ulduar bosses.
How Many Set Pieces?  Helmet, Shoulders, Chest, Hands, and Pants
Hunter Tier 8 Transmog: [10-Man Drop Locations]
Head: Helm of the Wayward Protector [Mimiron ] in Ulduar.
Chest: Chestguard of the Wayward Protector [Yogg-Saron] in Ulduar.
Hands: Gloves of the Wayward Protector [Freya] in Ulduar.
Legs: Leggings of the Wayward Protector [Hodir] in Ulduar.
Redeem Token Vendor: Bragund Brightlink [51,72] in Dalaran.