How to Acquire
In order to get this achievement Corvo Attano must kill 6 enemies in less than one second. He can upgrade Bend Time to Tier 2, use ite in an area with a large number of guards and kill them as quickly as possible.
Alternatively, he can go to an area with many guards, create a distraction to lure all the guards to one spot and cook a grenade so that it explodes on impact.
The easiest way is to knock out six guards, put them in a pile, and throw a grenade at them, killing the lot.