Story-based and unmissable.
Awarded for defeating the first 'boss' Taken [Stucky] in the Logging Area towards the end of Episode 1.
The encounter is signposted by a crate of pistol ammo and some torch batteries, and the encounter proper starts once you proceed past the crate.
Firstly there will be two waves of regular taken which are easily dispatched, then the boss proper will appear. The best way to handle him is to stay close to the ammo crate, and keep your torch on the boss as he rapidly darts between cover as best you can. and periodically the boss will stop/slow long enough to get a torch blast in. Eventually like with all Taken the darkness will burn away, at which point he'll stop darting around. Plug away with your pistol and he'll soon fall, netting you the achievement for your efforts.