Book of Tormtor
The Book of Tormtor was an artifact thought to have been left behind by the Ur-Daemon, which Despana used to create her undead horde, leading to the Undead War and collapse of the unified Elven Empire. It was found in the Southron Wastes, but was thought to have been destroyed in Maelshyve. It was rumored to be in the possession of Shar, last mentioned around the release of Animate Dead (730).
Behind the Scenes
Tormtor and Despana are Dark Elven noble houses in the Dungeons & Dragons "Forgotten Realms" campaign setting, seemingly first established on page 98 of "The Drow of the Underdark" (1991). Shar is both a name and a deity in this book. In later books House Despana was notable for its demon summoning, and works with House Tormtor in guarding city walls, though these details would need to be found in sources before 1996 to even potentially be easter eggs. Dharthiir refers to their word "Darthiir" on page 99, the surface elves, whom the dark elves hate for having driven them underground.
The Shar storyline in GemStone III ended abruptly (~ 1998) without going anywhere, but the 730 release was in 2005. Shar was rumored to be the daughter (or possibly lover) of Despana, seeking the Book of Tormtor to use the Broken Lands (at one point referred to as the "Arkati Workshop") to ascend herself to godhood. The details on Shar in GemStone are poorly recorded and hazy in general.