Borderlands

I would also like to mention that barrels count towards these kind of achievements as well. This will allow you to get the achievements much sooner because barrels are all over from the start of the game.

Red=Incendiary
Blue=Shock
Yellow=Explosive
Green=Corrosive

In order to obtain this achievement you will need to kill 25 enemies with the incendiary damage. You can tell which weapons have incendiary damage by the "Fire" icon located above the weapons picture. You'll find the that these are more effective against unshielded, flesh enemies which inlude Bruisers and Skags. You will know if the incendiary damage was the cause of death as the corpse will burn up.

There are 4 achievements in the game tied to elemental kills, now this can be a combination of kills with weapons, grenades and barrels that are scattered around the maps.

You can tell if your weapons and grenade modes have specific elemental effects as they have an icon on them:
• Red Flame - Incendiary
• Blue Lightning Bolt - Shock
• Yellow Explosion - Explosive
• Green Radioactive Symbol - Corrosive
The barrels are also colour coded:
• Red/Orange - Incendiary
• Blue - Shock
• Yellow - Explosive
• Green - Corrosive

The easiest enemies to kill will be unshielded enemies like Skags, Rakk, Spiderants and lower level bandits, however it doesn't matter if they have a shield if your weapon is strong enough.

Get 25 kills with a combination of weapons, grenades and barrels and the achievement is yours.