In this video I kill the target of the main story mission "Den of the Beast" before the game intends you to.
The door I am teleporting through using Assassin's focus is locked during this moment in the mission. For the Blowdart I think it is vital to have the cloud impact uogrsde active in order to do this.
If you kill him during this stage of the mission he will become semi-inactive (as he is near he end of the video), not respond to anything but his detection meter will still be active.
Although this was fun to do, this is sadly once again a main assassination mission where the target is kept in a random small room, allowing for almost zero creativity.