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After talking to Oz to update the quest he will direct you to kill 12 Dukaki. The Dukaki will be in the Kabarah Strip Mine. Follow the main road in Poeta and it will lead you to the mine. This road will twist and turn quite a lot until you reach the Kabarah Strip Mine but just keep moving forward. You will eventually run into it. Once at the mine find and kill 12 Dukaki and then return to Oz.
When you reach Oz and tell him you have successfully killed the 12 Dukaki he thinks you did a great job and wants to send you back to the mine to kill 3 Tursin Overseeers. So now you will need to turn around and walk back to Kabarah Strip Mine to find the Tursin Overseers. As you have already discovered the mine is not a very big place so you will not have any trouble killing 3 Tursin Overseers. After you killed these head back to Oz for a final time.

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Upon returning to Oz at the Melponeh’s Campsite he asks for a report of your killings at the Kabarah Strip Mine. Tell him you killed the 3 Tursin Overseers and he will gladly reward you for your troubles.
The Illegal Logging campaign quest is only 1 of many steps that need to be done in order to complete this campaign quest series.
Update: The Kabarah Strip Mine's name has changed to Timolia Mine. The quest still asks you to go to the Kabarah Strip Mine though.