This achievement is for defeating the final boss, a professor, in the game. At the first phase of the fight, you need to shoot him until he's damaged to the point where a cut scene occurs. Run away from his dynamite, as this can do a lot of damage. He throws it pretty regularly in both the first and second phases of the fight. Run around the platform to get him into view if he runs away. During the cut scene, he'll connect two pieces of an artifact, which will charge him with lots of power, and his eyes will now be glowing white. During the second phase of the fight, you have to avoid his dynamite, just like in the first phase, and blow up the pillars holding up the central fire eyed skull structure. A grenade launcher is available near the wall of the platform facing away from the skull. Use this to take out the supports. It will take two hits to destroy each one. Once that's done, you'll see a cut scene in which your enemy gets engulfed in lava from the skull. During this, you'll unlock this achievement.