Dishonored: Death of the Outsider

The first opportunity you have to compelte this is during Mission 05 once you interact with the eye of the dead god. Once you interact with the eye, directly behind you will be a body with a key that is required to progress the story. In that same area, there is a Envisioned bumbling around. Envisioned are tall pieces of shit that can one shot your sorry ass. I would suggest you pull out your coc.. electro gun and light his ass up with voltaic bolts. Once you have done enough damage to him, he will kneel down in which case you should run up and press left mouse button to send him further into the void. Cheevo popped.