Sojourner's Portal

The Sojourner's Portal was a magical item taking the form of a mirror that stood within the House of the Moon temple to Selûne in Waterdeep in the late 14 century DR. It was able to open gates to many other places.

Description
Standing at the end of a short corridor on the temple's second floor, between the cimeliarch (treasury) and dormitory, it was an antique, oval-shaped mirror with an ornate silver frame that was tarnished with great age. Although it seemed unremarkable, a detect magic spell or the like would reveal an aura of alteration magic. However, if one stared into it for several minutes, their reflected image was somehow altered. Different people saw different degrees of change, but those who did tended toward the view that the mirror reflected how a person truly saw themselves.

Powers
The primary power of Sojourner's Portal, and the one for which it was named, was to open one-way gates within the mirror to certain other places in Faerûn that were holy to the Moonmaiden. This could be done with a quietly spoken command word, one only known by high priestess Naneatha Suaril and a few of her closest advisors. The destinations were also secret, but among the possibilities were the sister temples of the Moonmaiden's Hall in Murann, Amn; the House of the Lady in Immersea, Cormyr; and the Temple of Silver Stars in Silverymoon in the North; somewhere near their allies at the Promenade of the Dark Maiden on Undermountain's third level; a fabled lost city of Selûnites in the South, such as ruined Minsorran on the shore of Lake Weng or even Myth Lharast, both in Amn; and possibly even the moon!

History
Amidst the havoc of Halaster's Higharvestide in the, the magic of the Sojourner's Portal became warped so that it worked the other way, and the mirror unleashed a crimson death and three vampiric mists from the depths of Undermountain into the heart of the temple. They hunted and slew a number of priests before they were stopped; the vampiric mists were swiftly destroyed, but the crimson death fled into the sewers of Waterdeep and was lost. Meanwhile, Naneatha was able to redirect the gate, sending subsequent monsters—a sahuagin patrol, an ettin, two trappers, and a pyrohydra—into the crypts below Shar's Temple of Old Night in Calimport. In the year after, Naneatha reconsidered that a portal in the middle of her temple might just be a security risk.