The notes of Karl Zavnen, diviner in the service of Herzog Chelor of Ahlissa, on the site known as Icespire

...the robed one (presumably Torvish Hachalm, the mage assigned to Lezt Lechtfeur) descended into the room, passing the fearful guards. A bloody stain led from the room into the darkness of the caverns beyond. The robed one paused to examine the blood, and then set off to follow the trail, a small group of guardsmen following behind him....

...near a fork in the caverns, the trail ended. From in the distance, the crash of the waves upon the rocks could be heard. There was no sign of whatever made the bloody trail, winding through the caverns. A scream rang out, and was abruptly cut off. Some of the guards panicked, and ran back the way they’d come. Most stayed with the robed one, though, and followed him deeper into the caverns, searching for (presumably) a missing comrade...

...the gates wouldn’t open, trapping the men within the keep. One tried to climb down the battlements, only to find himself devoured by something dark and formless. His screams echoed throughout the keep, causing men to pause in what they were doing and shudder in horror. None tried to go over the walls after the first...

...the robed one came to a chamber, half his guard missing, the other half shaking in terror. Within the chamber, madness dwelled. It struck the guards, as the mage tried to battle it. Once it had claimed the guards, their bodies frozen solid, it turned on the robed one and broke his mind to it’s service...

...the madness and the robed one ascended from the caverns to the keep, and found the guards trying to battle the minor horrors that had crept up from below. They were unable to stand against the madness that had accompanied their leader from the depths. Many died where they stood, frozen solid before they could even finish their screams of terror. Others hid throughout the keep, while a few sought refuge in the beacon. All perished as the horrors sought them out...

...the madness turned it’s baneful gaze about the keep, searching. It saw someone looking in, and reached out. A scream was heard. A woman’s scream. Another watcher was found and swiftly destroyed. Then it turned it’s gaze my direction...

That was the last that Karl Zavnen wrote. He was found the next day in his chambers, in a state of catatonia. Over the next few weeks, he slowly managed to recover, but he is still unable to recall anything of the day that he wrote these passages, or of anything he saw. Perhaps it is best that he recalls nothing of it. I doubt the true horror of what happened would have allowed him to remain among the living for long.