The Pyro Achievement Icon
Kill 25 enemies with incendiary weapons
 How To
This achievement is unlocked by killing 25 enemies with any incendiary elemental weapons, or action skill with an incendiary artifact equipped. In order for the kill to count towards the achievement, the enemy must actually die due to the fire damage, not the bullet damage, so you may have to shoot an enemy until he is almost finished, and let the fire damage finish him off. You can track how many incendiary kills you have by checking the Challenge Log.