Dead Island Definitive Edition

This will unlock once you beat the mission Devastator which will conclude Chapter 8 and ACT 2

You will get this achievement by playing through the story. After you give Supplies to the church, you'll bring the truck back to the Slums and that will end Chapter 8. Two more quests and you will get a quest called "Devastator" Where they talk about doing a certain task. Once you complete this you will have Completed Act 2.

Quest *Spoiler*


Short Version:
Chapter: 9
Quest: Devastator

Hope this Helps! :D