The abandoned stargazing watchtower of Bogroot Swamp. Boasts a grand mural of the heavens.

Within the observatory, you find that the domed ceiling and walls are still painted with a mural of the heavens, marking each constellation. The great lenses, once used by the ancients to observe celestial movements, have fallen and cracked. - Bogroot Demon (RPA-ADV6)

A mural of the heavens decorates the entirety of the observatory interior;

Since your youth, you’ve known that each star in the sky is a window into another world. If there were a giant tall enough to reach the heavens, it could peer into every realm of the planarverse. Azema the Benevolent framed those windows, arranging them in constellations that represent the pantheon of Dragon gods, in whose image she forged Ulos and in whose name she brought order to the planarverse.

You let the ice slug crawl around the walls painted with a map of the heavens. It comes to rest near a star that forms the tip of the constellation Ninik’s Spear. - Bogroot Demon (RPA-ADV6)

Upon first arrival, it is clear that the Starlit Door had visited the site;

The roots of the mangrove used to extend to this island, but they have been sawed off several feet from the shore, their stumps painted with the Eye of the Starlit Door. - Bogroot Demon (RPA-ADV6)

Working your way inside, you encounter a Basilisk that has made its home here:

• Slay the beast.
• Scare it off into the swamp.

Once the encounter has ended, you find a Basilisk egg covered in slime to bring back to the Frogkin elder Mugbok in Sandhill Village.

After solving the puzzle of the observatory and unlocking a hidden chamber, you unearth the Rune Bones;

You discover an indentation in the wall that is shaped like a five-pointed star and set in the crown of the constellation Merrin, the Dragon goddess of the sea.
You hear a click, and then a grinding of gears. A door opens in the wall before you and leads you into an ancient durgolium chamber.
Inside the sack, you find a set of oversized knuckle bones, carved with runes, an ancient tool for divination. The bones hum quietly and glow when you touch them. - Bogroot Demon (RPA-ADV6)

Bertram Hoogna reappears at the Ancient Observatory to help you realize your intent for your monastery;

“The veil between worlds is thin here, so I was able to visit you again.” - Bertram Hoogna, Backstory Codex - Apprentice (RPA-BC)

• Let the spirits of your friends rest, and search the stars for new pupils to make a new order.
• Let the sprits of your friends rest, and search the stars for where the Dragul who took their lives are, to exact your revenge alone.
• Unleash the spirits of your friends to make a new order with them by your side.
• Unleash the spirits of your friends upon the Dragul who took their lives to exact their revenge.