~#~ Pyromancer ~#~
This achievement requires you to score a kill with the Engineers Pyro Mine.
First of all, you'll need to purchase the Pyro Mine skill and equip it to one of your D-Pad buttons. With that done, it's a simple case of finding the most effective spots to employ your new incendiary.
The Pyro Mine's explosion is noticeably less damaging than a normal mine. Due to this, it is much better deployed in a confined space, where the small, lasting area of effect is much more effective. Great places to deploy your mine are something you will learn with very little effort during play, but placing them near Primary Objectives (offset them slightly, so they are activated (not just stood-on) by approaching enemies) is a near-guaranteed way of scoring the one kill for this achievement.
Placing Incendiary Mines is a skill made up of two others - using Mines to block off essential/unavoidable routes, and using Caltrops to warn/weaken against invading enemies. With a little experimentation you're sure to find a great place to set this up, just remember to keep your foe distracted so they burn before they can flee!