If memory serves, this is an item you can find in the Stone Sea where the Stonestalkers are, in the area where you move a rock to drain a little lake, giving you access to a beastman corpse. On some of my playthroughs I could find the Everwell there : it's a skull that goes into the quest items section of your inventory, and is described to be a/the source of everlasting ink the Sages had. I suspect you only get it if you choose to go to the Burning Library during Conquest and give the Sages advance warning (but not sure about that).
Does anyone know what it's good for ? I thought it might be used to replace the Silent Archive as an artifact to maintain the building's stability without sacr
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