In Episode 4, your car will be picked up by a swarm of Vampirz and dropped in courtyard in front of a giant fleshy nest. All you have to do to destroy it is hit it with four explosive bottles. There are lots of bottles of flammable liquid scattered around the courtyard, so just grab them, throw them at the body of the nest, and shoot them with the gun when they get close. Move quickly to avoid the swarming Vampirz. After four direct hits, the nest will be destroyed and the achievement will unlock.