You can get either
Deductive Mind/Captain Obvious achievement or
Fine Investigator achievement!
Speak with
Sunkiest at
Aurea city
For Deductive Mind achievement do this:
While speaking to
Sunkiest choose: Lizards did it!
To get
Captain Obvious achievement choose: ORCS DID IT
Only 4 clues are enough, here are they:
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For Fine Investigator achievement do this:
Find 5 more clues, 9clues in total needed for this achievement!
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
Come back to
Sunkiest to finish the quest