Battle the Leviathan at the end of Chapter 6. In Phase 1, dodge the tentacles when they jut out toward you and shoot the weak point at the base of the tentacles. During Phase 2, the mouth starts spitting explosives at you. Use Kinesis (
+
) to grab and throw (
) them back at the mouth. You can also use explosives floating in the room on the mouth. In Phase 3, it will use both attacks combined with poisonous gas in the chamber. Continue dodging the tentacles and throwing the explosives until you defeat the Leviathan and the achievement pops.