The savant aboleth Iltharshub is a member of a council of four savant aboleths that rule the deep city of Yolinithili. Well served by ample slaves and loyal aboleth mages, Iltharshub spent large portions of its time sifting through the ancient memories of its ancestors. It was thus with great shock that it stumbled upon a memory of an ancient ruin from the primal empire—an aboleth laboratory located only a few dozen miles away in a forgotten section of deep underground waterways.
Iltharshub pondered its memories of the ruins for several more days and came to realize that the building was constructed well enough that it likely survived the passage of eons. It decided there and then to claim the ruins and the fantastic treasures lost within for its own. It did not want to share any discoveries with its rivals on Yolinithili’s council, so it took only a single assistant and its most loyal and powerful bodyguard, a greater stone golem. It then set off to find the nameless ruins.
The PCs can encounter Iltharshub and its golem and assistant in any number of ways. They might stumble across the aboleths while exploring the flooded underground. They might be seeking out the same ruins, not realizing that the site is an ancient aboleth laboratory. They might also be hired by a powerful wizard who has learned that one of the leaders of the nearby city of Yolinithili passed by recently. The fact that a savant aboleth left the city intrigues the wizard greatly, and he sends the PCs to investigate in return for information, items, or spells they seek.