There is nothing to do inside the Herald's chamber!
Hint 1 of 6:
Did you look at his tomb? This crypt requires a special key.
Hint 2 of 6:
The key is in an alcove which can easily be missed if you pass it in the
tunnels.
Hint 3 of 6:
Leave his chamber and take the first left tunnel. At your first stop, turn
right and enter a small alcove with an altar and various artifacts.
Hint 4 of 6:
Look down and to the right of the altar. Click on the ornate chest and get
what is inside.
Hint 5 of 6:
Return to the Herald's tomb (right from the alcove, right at the junction).
Hint 6 of 6:
Open the tomb using the artifact.