This achievement is awarded for reaching sequence 10 in wolfpack mode.
In this mode, you and up to three other players will be playing a Manhunt game against the AI. In each sequence you will have infinite targets given, and you must reach a certain point threshold to proceed to the next sequence. You also have a timer, and will be given time when you reach the next sequence. The fewer players are present, the fewer targets appear (score thresholds are also lowered). You can do this solo (but I found it easier in a group).
As a result, you want to get the best kills possible (i.e. worth the most points - like a focus incognito kill, multi-kills etc) to move the sequences along as fast as possible. Sometimes extra targets worth time appear - kill them ASAP to get the time.
All you need to do is reach sequence 10 (not complete it). As there are 25 sequences, the first few are relatively easy (4 targets standing together for 4 focus multikills, etc). Keep your point total high and this will pop quickly. As a reference, it took my team <20min to pop this achievement.
This will pop ingame, as soon as you reach sequence 10. Good luck!