Message from the Empress is a hidden achievement/trophy in The Knife of Dunwall. It requires Daud to perform a drop assassination from the top of the statue of the Empress, attached to the Chamber of Commerce Building.
How to Acquire
Daud can start by making his way to the top of the destroyed building behind the Chamber of Commerce Building. From there, he can blink to the top of the statue and jump from it once an enemy passes close by on the ground.