Relith Tower

The top level teleportation fields are seen activating, allowing access to the stars above

The Relith Tower (also called The Starlit Tower) is a lost ruin located near the Barrier Peaks in Isonhound.

It was lost to the ages, but rediscovered in 825 PR, and subsequently lost again when the ranger who found it was sworn to secrecy by Wold Order...only to be found by cultists of Att-Annalo who were following the ranger.

About

The tower was constructed some point in the mid PR era by a fleet of Relith people who crashed into Quelmar from the stars above, likely another group escaping the iron claw of their Relic Dragon slavedrivers.

At some point, drawn by the psionic energies of the Relith people and their magitech, a MindSnare Naga took up residence in the tower's third level, it eventually wound up infecting Boros who in turn infected Vessel.

The tower held many strange blueprints, diaries, journals, and templates in a foreign language, all indecipherable even with Comprehend Language (because it's literally an alien language from the far realm/outer space).

The Teleporter

The original Relith who built the tower spent decades if not centuries researching Quelmar and its basic technologies in an attempt to make a functioning Galaxialider, a type of matter-phasing device that could teleport people off of Quelmar and back through the astral plane.

Not knowing how the technology worked, a group of heroes who arrived at the tower in 825 PR dabbled with it, accidentally turning on the teleporter in the process. When they put Alenka the Soul Star into it, it channeled its magic into releasing the souls held inside. However, due to the mis-calibration of the device, the souls were not teleported to far off spaces, but rather across Quelmar itself, causing a tidal wave of lost ghosts to wash over the world, including the very dangerous soul of the Herald of Tiamat Vezoth, who was teleported to Zobeck.

Still tinkering with magic they did not understand, the team then proceeded to teleport Tordek and Rocky into the stars above as well, turning them into constellations.

Fate

After the tower was infiltrated by cultists of Att-Annalo (who found the tower by following Reylendor, who visited the tower on a mission assigned by The Wold Order), the cultists ransacked the strange alien devices, and eventually smuggled in a hostage of their own: Echemus the crystal dragon of the moon. They hoped that using the fancy tech of the Relith people, they could funnel Echemus' celestial energies into their mortal bodies, making them even closer to being one with Att-Annalo.

A team of heroes including Herneldo, Markoth, Felicia, and Dug tried to stop the experiment, and in the process, the battle and overwhelmed technology caused the shaking and eventual collapse of the tower with all parties still inside. This should have been a disaster, however many survived, including Echemus, thanks to a deal made by Dug with a god of death that watched the events unfold from a distance: Silent. Their death ward saved the team, but doomed the cultists, and left the tower as a graveyard.