Speak with Explorer Mowi at the Temple of Earth in Deepholm.
We have a contingent of the Explorers' League in the chamber just to the northwest inside the temple.
They've been making increasing noises about something that the Twilight's Hammer is up to.
<name>, would you be a dear and see what they need?
You will also receive:
- 4,390 experience
- 22 (if completed at level 90)