Given by Gimblefixx in the quest Search for the Ultimate Story and which is later given to King Ak`Anon.
The key to using this key is a couple of things:
1: Put it on your cursor,
2: take off any levitation,
3: duck if you human or taller (I duck even as a Wood Elf sometimes),
4: Use the U key instead of mouse clicking.
When you do all 4, it usually works without a hitch.
Yther Ore.