You start the fire and throw the pinecone into the fire.
About a minute after the pinecone is tossed into the fire, Jathyl reappears smiling beatifically. Her quills and nails fall away before she fades into nothingness. She is laid to rest.
The Master promises that the monastery will see to it that the trees are protected. Having heard about sustainable harvesting from Chaul, they are intent to learn more about the topic.
Your group returns safely to Almas with the manuscript. After much heated discussion, the Society permanently relocates the Fleshforge Manuscript to the Grand Lodge. By that time, you have all been assigned your next mission.
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Primary Success: You recovered the Fleshforge Manuscript.
Secondary Success: You laid Jathyl's spirit to rest, granting her peace and preventing her from continuing to steal from the Pathfinder Society.
Congratulations!