For this achievement, your first step will be completing the all the single player story missions (yellow) in order to complete the story.
Now, you will need to replay the mission, and beat the par time of 35:00. To do this, open the menu, on the "Log" screen press
to view all the missions and select "This Ends Here".
Now you'll want to complete the mission as fast as possible in order to unlock the achievement. 35:00 is plenty of time, and you should remember the strategies that are needed to defeat the final boss. View the following video for more information on the final boss bottle and the level which I complete in 14:00, less than half of the required time: