Somehow I missed showing the rune behind the sewer grate. You can get this at pretty much any time as long as there isn’t a guard right above you. What I discovered was that even with all the guards out of commission the workers will attack you if you use your pistol to shoot the board in the sewer. I tried to pull the rune to me but that didn’t work in this case, but the crossbow breaks the board and won’t alert even the peaceful citizens of Karnaca allowing you to collect the rune and be on you way.
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