The crossover is with RA Salvatore's Dark Elf stories and with 'his' War of the Spider Queen series, particularly the first volume, Dissolution.

…

Homeland describes the early life of the dark elf, Drizzt Do'Urden, who was born in the drow city of Menzoberranzan, having been conceived as a sacrifice to the spider goddess, Lloth, in furtherance of his mother's political ambitions. Drizzt, however, was spared because, at the moment of his birth, his brother, Dinin, murdered their oldest brother, Nalfein.

Drizzt is a strange drow in several respects—he has lavender eyes; he is an exceptional warrior in a race of exceptional warriors; and (like his father, Zaknafein, but unlike most other drow) he has a conscience.

Shortly after graduating from Tier Breche, the drow Academy, Drizzt was chosen to take part in a surface raid led by Dinin. After travelling through The Underdark for more than a week, the raiding party found a suitable crack in the rock...

"You first," Dinin said to Drizzt. Drizzt looked at his brother incredulously, having no idea how he could pass through such a tiny crack.

"Come," instructed the cleric, who now held a many-holed orb. "Walk past me and continue through."

As Drizzt passed the cleric, she spoke the orb's command word and held it over Drizzt's head. Black flakes, blacker than Drizzt's ebony skin, drifted over him, and he felt a tremendous shudder ripple across his spine.

The others looked on in amazement as Drizzt's body narrowed to the width of a hair and he became a two-dimensional image, a shadow of his former self.

Drizzt did not understand what was happening, but the crack suddenly widened before him. He slipped into it, found movement in his present form merely an enactment of will, and drifted through the twists, turns and bends of the tiny channel…

…

Unnoticed, [the drow] lined the perimeter of the small glade where a score of faeries [surface elves] danced and sang.

Transfixed by the sheer joy of the elves' play, Drizzt hardly noticed the commands his brother issued then in the silent [hand] code. Several children danced among the gathering, marked only by the size of their bodies, and were no freer in spirit than the adults they accompanied. So innocent they all seemed, so full of life and wistfulness, and obviously bonded to each other by friendship more profound than Drizzt had ever known in Menzoberranzan…

Then Drizzt's keen ears heard the soft thrum of a dozen tiny bowstrings. The elven song carried on a moment longer, until several of the elves dropped to the earth.

"No!" Drizzt screamed in protest… The denial sounded just like another war cry to the drow raiders…

One terrified female, dodging this way and that, came before Drizzt. He dipped the tips of his weapons to the earth, searching for some way to give a measure of comfort.

The female then jerked straight as a sword dove into her back, its tip thrusting right through her slender form. Drizzt watched, mesmerised and horrified, as the drow warrior behind her grasped the weapon hilt in both hands and twisted it savagely. The female elf looked straight at Drizzt in the last fleeting seconds of her life, her eyes crying for mercy. Her voice was no more than a sickening gurgle of blood.

His face the exultation of ecstasy, the drow warrior tore his sword free and sliced it across, taking the head from the elven female's shoulders.

"Vengeance!" he cried at Drizzt…

Only a moment later, another elf, this one a young girl, broke free of the massacre and rushed in Drizzt's direction…

He brought the scimitar down in a mighty sweep, watching Dinin out of the corner of his eye as it whisked harmlessly past the child. In the same motion, Drizzt followed with his other hand, catching the girl by the front of her tunic and pulling her face-down to the ground.

She screamed, unharmed but terrified, and Drizzt saw Dinin thrust his fist into the air again and turn away.

Drizzt had to work quickly; the battle was almost at its gruesome end. He sliced his scimitars expertly above the huddled child's back, cutting her clothing, but not so much as scratching her tender skin. Then he used the blood of the headless corpse to mask the trick, taking grim satisfaction that the elven mother would be pleased to know that, in dying, she had saved the life of her daughter…

The cover of Homeland, painted by Todd Lockwood, showing Drizzt and his magical panther, Guenhwyvar, leaving the city of Menzoberranzan.

Another part of the Underdark. The cover of Exile, painted by Todd Lockwood, showing Drizzt in the Illithid Cave. Drow have certain innate magical abilities, including the ability to create a globe of darkness about themselves and the ability to levitate (though the latter disappears when they are on the surface). The figure at the far left is the re-animated corpse of Drizzt's father, Zaknafein Do'Urden, sent by Drizzt's mother to destroy their son.

The Underdark is an entire world beneath the surface—a harsh, perpetually dark realm of tunnels that extend for miles, some forming caverns thousands of feet across—the largest are like miniature versions of the surface, with hills, valleys, underground rivers, and lakes. Some places are dimly lit by glowing rocks, luminous crystals, or phosphorescent moss, lichen, and fungi, and many are filled with bizarre plants that may be hostile or poisonous. The most precious resource here is fresh water, since the Underdark has no rain and its inhabitants must rely on whatever filters down from the surface.

Drow society is matriarchal—female drow are larger, stronger and crueller than their male counterparts and, whereas noble females are raised to serve as priestesses of the spider goddess, Lloth, males are confined to the inferior roles of wizard, soldier and father.

Menzoberranzan is nominally ruled by a council composed of the Matron Mothers of the eight highest-ranking noble houses. In reality, the houses are locked in a constant, chaotic struggle for supremacy.

The city itself has no army, but each noble house has its own highly trained soldiers and is expected to contribute some of its troops towards the defence of the city, including the regular patrols of the surrounding tunnels and the occasional surface raids. All military action is supported by the spells of drow wizards or drow priestesses, though wizards are not permitted to accompany surface raids for fear that their magic will misfire under surface conditions.

Menzoberranzan itself occupies a triangular cavern, two miles across at the widest point, with a ceiling that rises a thousand feet, and a floor studded with stalagmites—which the drow have transformed into castles with sculpted walls and spires lit by the soft, tinted glows of permanent faerie fire.

The city is divided into distinct districts, each occupied by members of particular class. Qu'ellarz'orl, the Place of Nobles, is a raised plateau in the southwestern corner, shielded from the lower city by a forest of giant mushrooms. Narbondellyn, home to the most ambitious noble houses, arcs beneath its slopes. The Bazaar is an ongoing trade fair. And Donigarten, a natural lake set at the lowest end of the cavern, serves as the city's reservoir, irrigates the moss beds and fungi dungfields, and teems with fish and eels (and, possibily, more dangerous creatures). An island at its centre is home to the city's herd of sheep-like 'rothe'.

Tier Breche, the drow Academy, consists of three schools: the pyramid-shaped Melee-Magthere for warriors, the sculpted stalagmite tower of Sorcere for wizards, and the spider-shaped temple of Arach-Tinilith where the (female) clergy of Lloth are trained. Tier Breche is located in a side cavern on the northern edge of the city, accessed by a massive stone stairway.

Major products of the city include body dyes and augmentations, chains, high-quality edible mushrooms, everdark ink (made from deep dragon scales dissolved in acid, prized by wizards), fine weapons, giant slugs (sold as draft animals), herbal medicines, kayaks, liniments, musical instruments (flutes and drums as well as other percussive instruments), obsidian carvings (including "black glass daggers" favored for sacrificial use in some surface cultures), perfumes (particularly those that function as personal body scents or aphrodisiacs, or capture the fragrance of surface-world flowers), poisons, potions, pyrimo meat, riding lizards (bred and trained), rothe products, scented oils, slaves, spells, spiced sausages, stone sculptures, surgical services, textiles, tortoiseshell combs and inlays (made from the shells of giant Underdark turtles), ulaver wine (spiced, sparkling, luminous green wine made by the Ulaver family), and even water (prized by long-distance travellers).