Hall of Reflected Moonlight

The Hall of Reflected Moonlight was a chapterhouse of the Order of the Blue Moon, a group devoted to Selûne and Mystra, hidden within the Red Rocks in the Sea of Swords off the Sword Coast North in the late 14 century DR. It was formerly the fortress of Black Logan's Keep.

Location
It perched atop a jagged stone spur in the southern Red Rocks, just to the north of Waterdeep. A rocky sandbar, which was only apparent at low tide, joined the islet to the mainland, where a narrow trail made its way to the High Road.

Structure
Especially small for a fortress, it comprised only three stout towers joined by walls to form a triangle. These were surrounded an approximately ovoid outer wall.

To reach the fortress without the aid of flight, one had to cross the sandbar and then scale a series of very short stone steps carved out of the rock. This stair ascended through a number of switchbacks and five gates until finally reaching the fortress's lower parts.

Otherwise, on the western side of the islet was a sea cave big enough for a small ship to dock in. From there, a winch-driven elevator carried visitors up a narrow shaft.

Inhabitants
The Hall of Reflected Moonlight could house no more than sixty people, but it only needed twenty knights of the Blue Moon to effectively defend it.

History
A local legend claimed that the fortress was built by one Black Logan, who was supposedly a peer of an early warlord of Waterdeep, but it wasn't specified which. In any case, the story went that the two came into conflict, Black Logan escape to his island keep, and the warlord's army laid siege to it for over a year. Finally, Black Logan suffered heartstop and died and his troops tossed the body off the wall as a sign of surrender.

Rumors & Legends
The legend went on to say that the ghost of Black Logan haunted the keep and hungered for revenge. However, visitors to the later Hall of Reflected Moonlight had seen no sign of it, so either the story was false or else the Order of the Blue Moon had made a deal with Black Logan.