To get this trophy/achievement you need to kill EVERYONE inside a settlement or town. You should be able to do this at any town, and I’ve seen reports from people who got it at Grackle, Quickbend, Valford and others.
I personally got this in the town of “Horton” on the far South East of the map.
I would recommend making a save before getting this trophy as you’ll rack up a large bounty on your head for killing so many innocents and possibly vendetta’s as well.
Once you’ve picked your town and made your save. You need to make your way through and kill everyone possible. I personally found it easier to pick a smaller town with less people and to have a full possy as they’ll help fight and draw attention away from you. This can be a tough fight depending where you do it as many people will fight back and some people may be werewolves or sirens in disguise.
Once you’ve killed everyone (and I would run back through town a second time to double check) you’ll get the trophy/achievement when you travel away from the town.
If you miss anyone and come back most people will re-spawn and they’ll be hostile towards you, so taking the extra time to make sure it’s completely clear is best.
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