I've created a 57 second YouTube Short guide showing how to get the Exterminator achievement by killing the Leviathan.
The Leviathan is the boss in Chapter 6: Environmental Hazard. This boss fight has 3 phases.
- Phase 1: Dodge the tentacles when they try to hit you and shoot the swollen yellow targets.
- Phase 2: Dodge the yellow pods the Leviathan shoots at you. Catch them or the explosive tanks around the area and shoot them into the Leviathan's mouth.
- Phase 3: You'll now be dodging the tentacles and pods. The Leviathan also releases a poisonous cloud that fills the area and doesn't dissipate. Watch you air supply and use O2 tanks as needed. There are some floating around the area. The goal remains the same. Shoot pods or explosive tanks into its mouth to kill it for good.
https://youtube.com/shorts/NHa_PAhqw4s?feature=share