monster of nightmares
Sinister and more than patient and cunning enough to lie in wait for ambush, this would appear to be a fairly prototypical specimen of its kind. It can ennunciate a dialect of Undercommon via its multiple throat-orifices, though no doubt it was merely condescending to express its frustration to the undead nuisances which had stolen away the treasures it came seeking in Lamnuathwete. Although it arrived with a retinue of wretched slaves, it declined to engage in combat when the terrain and stakes were not in its favor.
To be sure, the ire of a nightmare out of time may prove to be of no small concern, but the more immediately pressing question is why such a monster from the deeps is found so far inland and how it could possibly have known to arrive at this temple-shrine with this suspiciously accurate timing in order, ostensibly, to abscond with the treasured souls of saints stored within?