This achievement is story-related and cannot be missed.
When you are going after the Penguin in the museum, you will eventually come to a room that has an arena like setting arranged. In this room you have to fight waves of enemies that the Penguin sends after you. The last wave features a new enemy type that is similar to the titan infused enemies from Arkham Asylum. perform a super stun( 3x
) to take him out. You can use him to take out the other goons as well.
(video credit: Batman Arkham Videos)
Hope this helps you guys!
Any improvements? Please let me know in the comments below !