Extinction

Extinction by Lisa Smedman is the fourth book in the War of the Spider Queen series.

"Lies, Faith, and Oblivion.

The Queen of the Demonweb Pits may have turned her back on even her most faithful servants, or she may now hang lifeless in her own hellish webs. For one priestess, the only course left open to her is to discover the truth, even if she must return to a place from whence few have returned even once—a place where souls of the dead go to serve for eternity. For another priestess, the prospect of an afterlife without the Spider Queen drives her into the arms of another goddess, shattering the tenuous alliances that have brought the drow to the threshold of the Abyss."

Summary
The group of drow adventurers—Quenthel Baenre, Pharaun Mizzrym, Jeggred Baenre, Valas Hune, Ryld Argith, Halisstra Melarn, and Danifae Yauntyrr -- continue to seek answers about the Silence of Lolth after fleeing House Jaelre. Quenthel sends Halisstra to Menzoberranzan to report on their progress, then orders Pharaun to summon the glabrezu Belshazu in order to determine a way to return to the Demonweb Pits. While the others are distracted with the demon, Ryld sneaks off to join Halisstra.

After this point, the novel revolves around three distinct plot threads. After abandoning the group, Halisstra and Ryld run into followers of Eilistraee once again. Halisstra, her faith in Lolth now shaken, decides to convert to the worship of Eilistraee, despite Ryld's doubts. The two continue to develop a relationship that they even come to term "love," an emotion usually unknown to the drow. After killing a spider as a test of Eilistraee—an unforgivable act in pure defiance of Lolth—Halisstra has a vision telling her that her destiny is to find an ancient magical blade called the Crescent Blade. The blade is said to be able to cut through anything; she realizes she can use it to slay Lolth. The blade, however, has been lost in the Cold Fields by Halisstra's ancestor, Mathira Melarn, so Halisstra sets out to find it, Ryld following despite being ordered to stay behind. The guardian of the blade (in that the blade lay in its stomach) is a purple worm, which Ryld helps defeat after Halisstra is swallowed whole by the worm. However, Ryld is badly poisoned; Halisstra retrieves the blade and summons a mount to ride to the forest edge seeking help. Once there, she collapses with cold. She awakens to Feliane and Uluyara, priestesses of Eilistraee, healing her and Ryld of their wounds.

Meanwhile, in the World Below, Quenthel, Jeggred, Danifae, Pharaun, and Valas follow Belshazu's lead for a route into the Abyss: a ship of chaos that can traverse the planes. They travel to Lake Thoroot and Valas, given a spell of water-breathing by Pharaun, scouts out the water on the search for Zanhoriloch, an aboleth city where they might locate additional information about the ship of chaos. Valas is captured by the aboleths, who turn him into a mutated sea-dwelling drow. Valas manages to escape and contacts his companions. Pharaun returns him to drow form via polymorph spell (which can potentially be dispelled). Pharaun and Danifae then go to Zanhoriloch to parlay with Oothoon, the matriarch of the aboleths. Pharaun openly offers to give her Quenthel as payment to knowledge of the whereabouts of the ship. Danifae warns Quenthel, who turns the betrayal around by working with Oothoon to fake her death and allow Pharaun to be eaten. However, a contingency spell cast of Pharaun allows him to escape and the group sets off together again, this time for the Lake of Shadows where the ship of chaos is located. They find the ship stuck in a permanent whirlpool, but Pharaun is able to bind the uridezu captain and set it a sail.

Throughout all of this, Menzoberranzan has been under siege. Gromph Baenre, missing for several weeks after being imprisoned by Lichdrow Dyrr, escapes his prison with the help of his rat familiar Kyorli and a mindflayer named Sluuguth, whom Gromph tricks, through promises of great power, into casting a spell that frees him and imprisons the caster in an axe of souls. After bolstering the defense of the besieged city, the freed Gromph gathers the mages of House Baenre to attempt to kill Nimor Imphraezl through a special scrying gem. With each attempt either the spell is turned against the caster, or Nimor uses one of his rings to retreat to the Plane of Shadow before he can be killed. Taking advantage of this, Gromph and Andzrel Baenre approach Nimor in the disguise of tanarukk warriors from the Scourged Legion. Gromph tricks Nimor into holding a prism of light that has been covered in glue. When he retreats to the Shadow Plane, he is then trapped there since a patch of shadow is required in order to return to the Material Plane. However, the light from the magical prism leaves Gromph blind. His attempts to heal his eyes fail, so he masks the disability by magically viewing the world through the eyes of his rat familiar.

Main characters

 * Halisstra Melarn, former First Daughter of House Melarn of Ched Nasad
 * Ryld Argith, master of Melee-Magthere
 * Valas Hune, scout of Bregan D'aerthe
 * Pharaun Mizzrym, master of Sorcere
 * Quenthel Baenre, priestess of Lolth
 * Jeggred Baenre, draegloth
 * Danifae Yauntyrr, battle captive of Halisstra
 * Gromph Baenre, Archmage of Menzoberranzan

Supporting characters

 * Andzrel Baenre, weapons master of House Baenre
 * Belshazu, Jeggred's glabrezu father
 * Feliane, elven priestess of Eilistraee
 * Kyorli, Gromph's rat familiar
 * Nauzhror Baenre, acting Archmage of Menzoberranzan
 * Nimor Imphraezl, prince of the Jaezred Chaulssin
 * Oothoon, aboleth matriarch of Zanhoriloch
 * Triel Baenre, matron mother of House Baenre
 * Sluuguth, illithid in league with Nimor
 * Uluyara, drow priestess of Eilistraee
 * Yarno, werewolf boy

Creatures

 * aboleth
 * glabrezu
 * illithid
 * jade spider
 * mane
 * phase spider
 * purple worm
 * stirge
 * uridezu
 * wight
 * wraith

Locations
Surface
 * Cold Field (near Harrowdale)
 * Cormanthor and Myth Drannor
 * Velarswood

Underdark
 * Lake of Shadows
 * Lake Thoroot and Zanhoriloch
 * Menzoberranzan
 * Northdark