Hidden sanctuary in 0600 opened by the Adamantine Coin (coin-slot key in a pair of large stone doors). Mansion with a great hall; a copper dragon held the posting for ~1000 years. Crescent insignia matches the coin.
Discovered in 2026-06-27. The party recovered a second Adamantine Coin, the holo-disk Serenity, and a gold-bound personal journal here.