Bring the Skin of the Great Sandworm, 2 Idols of War, 5 Stone Scarabs and 5 Crystal Scarabs to Kandrostrasz inside Ahn'Qiraj. You must also attain Friendly reputation with the Brood of Nozdormu to complete this quest.
You seek to prove your worth to my kind, mortal? Very well, perhaps we can be of mutual assistance.
The ancient sandworm, Ouro, is a being of legendary power. He is rumored to have been created by the Old God himself as a mockery of life.
His skin is unnatural... thick, nearly impregnable, yet it's flexible and allows him to move with the speed and grace of a much smaller creature.
Bring me a sample of his skin along with other minor components and I shall craft you leggings of great power.
Yes... the worm's skin will make for an excellent protective layer. Combined with the strongest parts from the Qiraji we've destroyed on our way here, this should make for a formidable piece of armor. May it aid you in facing the unspeakable horrors that await inside!