WoW Transmog — Browse All Transmog Sets
Browse all 3,100+ World of Warcraft transmog appearance sets. Filter by expansion, armor type (Cloth, Leather, Mail, Plate, Cosmetic), and PvP sets. Track your wardrobe completion across all expansions.
Browse transmog sets from raids, dungeons, PvP, and quests across all expansions. Filter by armor type (plate, mail, leather, cloth) and source. Track which appearances you own and which you still need via Battle.net sync.
Battleplate of the Highlord
Plate set. Warlords of Draenor. Doesn't allow bottom half of a tabard through :(
Battleplate of the Highlord is a transmog appearance that can be obtained as a reward from the Cache of Nightborne Treasures.
Complete Emissary of War weekly quest
Complete the weekly event quest "Emissary of War" to receive a 
Cache of Nightborne Treasures. This quest offers Heroic-quality rewards with a minimum item level of 885.
Open the cache
Open the Cache of Nightborne Treasures to receive transmog rewards, which may include Battleplate of the Highlord.
Tips
Cache quality is determined when you obtain the mission, not when you complete it. Mythic raid kills will result in a higher-quality cache than Normal difficulty clears.