Steps to reproduce
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Take the Writ "The Lost Tunnels", go to the area to complete it, kill some monsters get to boss room, etc etc.
Expected result
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Kill everything you need to kill, Golem spawns, kill that too.
Actual result
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Kill everything, Rust Monster spawns instead of Golem, quest is never complete.
Screenshot(s)
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Notes
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I think it's a safe assumption that this was just an oversight, and most likely a known bug, but I just wanted to post this anyway just in case.