This achievement belongs to the first Two-Face side missions.
In these missions a group of Two-Face's goons tries to steal money from the various banks in Gotham. This bank is located in Bleake Island.
These missions play like every other predator challenge, meaning you have to sneak your way through it.
At the start of the mission there is a alarm ringing. This serves as an opportunity to take some of the thugs out, without them noticing anything. If you get seen, they will start to search for you and the alarm will be deactivated. So make good use of this phase because there are quite some guys to knock out.
Personally, I found it useful to hide near the escape car so I could start some fear combo-takedowns.
If you need more detailed help, please refer to the video below!
(Video Credit: Marcus Shomo)
Hope this helps :-)
Any improvements? Please let me know in the comments below!