Far to the southeast of the Inventor's Library, on the slopes to the north of Dun Niffelem, is a camp bearing my name. The Explorers' League representatives seeking the second half of the key are based there. Bring me the maps and the notes they've made and we should be able to track down the other key half.
Those iron dwarves will pay for this! There's little we can do now, and we have to focus on finishing the key. But once I get into the halls of Ulduar, the irons and their masters will answer for what they've done!