Here's my save for unlocking the 'Destroyed The Destroyer' achievey. It's a modded save I downloaded and played through. It has some class modded weapons, so credit goes to whoever created them. Just run through 'Eridian Promontory' to get to the boss fight. Waste his @$$ with any of the modded guns and the achievey will pop.<br />
Upon loading, the following achieveys will pop, if you don't have them already. 'There are some who call me...Tim', 25 kills for corrosive, explosive, and incendiary weapons, and 25 kills for ramming with a vehicle. 'Discovered Eridian Promontory' will also pop. Get a kill with Bloodwind and 'Careful, He Bites' will unlock. After the scene with Steele, 'Paid in New Haven' will pop. Then just finish off the boss for the final achievement.