This lonely edifice, standing proudly on its rocky promontory and nearly surrounded by the waters of the Nyr Dyv, is visible for miles in all directions. The promontory juts into the water of the lake for nearly half a mile, and for most of its length is barely two or three paces wide across its top. The surface is broken rock, so rough that a person must slow his pace to a crawl in order to walk here.
Tenser’s castle, dominated by its Great Tower, stands on a rocky outcrop overlooking Midbay. High-walled, with a magically reinforced gatehouse, drawbridge, and portcullis, it is nigh on impossible to raid. Magical illusions and distortions mask its traps and defenses, and a network of permanent wizard eye globes allowed Tenser to scry any part of his home with complete accuracy whenever he wished.
Since Tenser’s death, the sirens, swanmays, selkie, nymphs, and halflings he befriended still visit, in the hope that their friend may yet return. None enters the castle, save for Jallarzi Sallavarian, the executrix of Tenser’s will. She alone holds the keys to the castle, although she rarely visits now that Tenser’s bequests have been fulfilled.
Tenser did not leave possession of his home to anyone. Since his death, a programmed sequence of events has begun in the castle with a momentum all its own. Golems rearrange furnishings and the mobile elements of extraordinary magical runes and spheres; castle walls shift themselves; automatons enact seemingly meaningless sequences of actions; and from the deepest dungeons of the castle, strange grinding and whirring sounds are dimly audible. What this all portends is probably unknown to anyone, even Mordenkainen himself.
For anyone planning to loot the castle, the defenses are formidable—traps, golems, automatons, illusions, planar gates woven into descending nets, endlessly recursive catacombs, tesseract complexes, and much else besides.