Ancients of Ooga

You will get this achievement by naturally playing through the story. It is unlocked in the fourth level of the Realm of the Stinkers, "Intervention." You have to "sober up" 4 stinker Ooganis by removing them from the slugs. Once you deal with the fourth by tossing his friend in the clean water, the mission ends and the achievement pops.

You will unlock this in the fourth mission "Intervention" in the Realm of the Stinkers. Once you have sobered the fourth stinker, the mission will end and the achievement will unlock.