Blackstaff Tower (previously Arunsun Tower; renamed by Khelben in 1322 DR) was the home of the original Blackstaff Khelben Arunsun in Waterdeep as well as of his successors to the title of Blackstaff. The foreboding structure was one of the most recognizable landmarks in Waterdeep's Castle Ward.
Structure
Exterior
Blackstaff Tower's main entrance was on Swords Street. There was also an apprentice's gate, through which apprentices could gain access by touching the gate with a left palm. The tower was surrounded by a 20‑foot (6.1‑meter) wall.
The tower appeared to be made out of smooth black stone, with no windows or doors. From the outside, the structure appeared to be a three-story stone tower, but inside, there were at least a dozen more levels, and some of these could only be reached by magical means. Everything connected to the central stairwell, although magical passwords were required to transport to certain areas of this stairwell. The three levels visible from the outside were all freely accessible via simply using the stairs.
The tower had the ability to repair itself, along with its outer walls and gates, when damaged, and this process could be helped along by Laeral Silverhand. After an attack in which a wall was demolished, the tower was back to normal the same day.
Interior
From the inside, windows appeared to show what was going on outside, but these were illusions. The interior (but not the exterior) of the tower was warded against magical intrusion. The tower was protected against scrying magic.
Rooms were connected to the central stairwell and entry hall, which was full of floating doors and arches. Many alcoves and shelves covered the walls of the stairwell, displaying magical items and artifacts, and although they seemed unprotected, a command word was needed to remove any of them. The items changed on a regular basis, so returning to the same stairwell on another day might result in seeing different items. Leaving the dormitories without issuing a command word would lead to the second level's stairwell.Saying the command word nhurlaen in the stairwell took one to the study.
On the top floor of the tower was a study and a scrying chamber. There was also a parlor where Khelben displayed his art. In the library was one-way dimensional door to Candlekeep (the other side of the door led to Jester's Court nearby). As of 1374 DR, the tower's entry chamber contained a wardrobe that Khelben was able to use to access almost any closet in the tower. In the tower's kitchen, Khelben liked to serve cups of roasted chicory.
Tunnels linked the tower's basement to Piergeiron's Palace and other locations in Waterdeep, which could be accessed by uttering the command word vhuarm. One such tunnel could be accessed at Northspur Rock on Northspur Landing on the Talltumble Stairs in Mountainside.
Blackstaff's study
The blackstaff's personal study could only be reached by the blackstaff themselves or people they personally trusted.
The study itself resides in a pocket dimension that would change it's interior based on the current blackstaff's personality and character. Vajra Safahr, the current blackstaff, would have her office resemble the infinite void of space with beautiful stars and constellations floating around in it. The floor would give off the effect of droplets of water falling inside a small puddle when walked on.
History
The Tower was originally the home of Khelben "Blackstaff" Arunsun, his apprentices, and his consort Laeral Silverhand.
After the death of Khelben, his heirs to the title of Blackstaff used the tower as both a home and a place of power. In fact, the tower became so linked to the Blackstaff that, upon the death of their master, the heir must immediately travel to the tower. On at least two occasions, the Blackstaff died outside of the tower and the heir was driven insane until they returned to the tower.
Beginning in 1479 DR, Vajra Safahr became the youngest Blackstaff to occupy the Tower.