Shades of Gray
In Nightal, 1375, Vhaeraun was slain at the hands of his sister Eilistraee. She absorbed his power, and her priestesses got to work absorbing his church. For the most part, they succeeded; a splinter sect, comprising much of the eastern Underdark and surface drow, continues to venerate Vhaeraun under the prophet Rylaun Greyshade.
In 1377, Shade of the Ilythirii began assembling a warband for an unprecedented gambit. Acting on her own initiative, advised by the divine voice of Eilistraee herself, and working with allies Kyrin Lothandrien of Silverymoon and Driev, Portal-Master of Delzoun, she began to secretly assemble a crusade.
In the wake of the destruction of Hellgate Keep, there existed the possibility to harness the power of the resurgent Silver Marches. However, her plan required surprise, and no nation could mobilize without anyone noticing. Thus, she led her enemies in the Underdark to believe she was massing an army to conquer the ruins of Ched Nasad and build a base there.
In truth, the target was something far more ambitious: Menzoberranzan itself.
She built a coalition of the willing, an army 2,000 strong, consisting mainly of her own elite Ilythirii warriors, but also of elves, dwarves, men, and even orcs, all of whom had plenty of reason to hold a grudge against the drow.
The plan hinged on Kyrin's ability to make good on a promised epic spell, which would hijack the existing portals within Menzoberranzan to allow the army to teleport into the city's wards. Of course, the faerzress would block any such attempt, high magic or no, but that part Shade insisted would be taken care of.
When the day came, the army assembled in the staging grounds, and, rather than walk into an ambush the drow of Menzoberranzan had set up for them in Ched Nasad, they initiated their teleportation spell. At the same time, Eilistraee made a fatal blunder in her divine sava game with Lolth, which turned out not to be such a blunder after all.
She sacrificed herself to save the drow, a move Lolth could never anticipate, as she is incapable of contemplating the concept of self-sacrifice. Eilistraee died, but in her death, she redeemed as many of the drow as she could. She could not change their minds, or affect their will, but she could banish the demonic taint that first infected them before the fall, in the ancient prehistory of their people.
Nearly a fifth of all drow, perhaps those most likely to pursue a greater good after their redemption, or perhaps just at random, found the demonic taint purged from them. Many of their most evil impulses were silenced, and their elvish sense of empathy, long suppressed, became more acute. These drow were marked, for better or worse, by the fading of the red from their eyes, in favor of the natural and varied eye color of elves.
Eilistraee also purified the faerzress in Menzoberranzan, wiping it clean of the demonic influence of Lolth. Her hold over the faerzress faded, and it became as it once was, long ago: a sustaining magical force, a blessing to all drow equally, a gift from Araushnee.
The door was left open, and Kyrin walked through, with an army and a cause.
The Fall of Menzoberranzan
The Crusade penetrated the city, pouring forth through portals within the fortress of House Baenre. Kyrin and Shade confronted the matron mother herself, who struggled in the fluctuating energy of the faerzress to find her magic. Gromph responded to her mental call and teleported in to defend her.
The battle was fierce, but the drow were at a disadvantage; Kyrin and Shade had prepared for this specific battle, but the Baenres had not even considered it a possibility. Worse still, their tainted drow magic was running wild in the newly-purified faerzress.
Even as an army of dancing swords held Triel's honor guard at bay, Shade bested the matron mother and subdued her. When Gromph saw this, Kyrin offered him a chance to surrender. Instead, he whispered a string of power words. The first transformed the house honor guard into draegloths, driders, yochlol, and all manner of uncontrolled demons who would likely attack the elves before turning on one another. The second triggered a sequence of catastrophic sonic explosions which annihilated the tower of Sorcere, and the priceless magic artifacts therein. The final word teleported him away in a burst of hellfire, searing the elves but only empowering the demons.
Of course, Kyrin isn't a moron. An old friend had crafted some very special feather tokens to bring in the reserves. With an odd cracking sound, a handful of golden feathers became Driev, Calahan, and Aram. The demons didn't stand a chance.
Outside, the revolution had begun. Once the compound was secure, the army reorganized, bursting forth from the gates with Shade at their head. Opportunists of every clan had gathered nearby, hoping to seize power in a moment of weakness from the ruling clan. When they saw emerged from the gate, they had no simple response.
Shade's voice rang out across the whole cavern, compelling all true drow to rise up, to overthrow the old order, to expel Lolth from Menzoberranzan. Many, tainted or otherwise, were all too glad to contribute to the chaos, for good or ill. Many with grudged against Lolth or the houses were quick to take advantage of the situation, seeking out specific or random targets to take out their aggression.
Wisely, most of the other clans simply slammed their doors and hid behind their wards. Most rebellions quickly burned themselves out, and this one, they hoped, would be no exception. Some of them made preparations to retreat, in case the unthinkable happened.
Thousands died in the chaos--mostly slain by random, violent commoners--before the crusade could bring order to the city. She gathered a mob of rebellious drow to siege Arach-Tinilith--not because she needed their help, but she wanted them to witness.
A coven of dwarven stonesingers stepped up to the tower, shut tight against any possible intrusion. They produced great horns of brass, which weighed heavily against the stone. They blew the horns, in a long, continuous blare, which slowly gained intensity. The horns resonated against each other, and soon the cavern itself seemed to waver in time with the low wave.
Arach-Tinilith was on shaky ground. All lesser nearby structures crumbled as the cavern floor warped and quivered. Cracks began to form around the base of the structure, and it was visibly shaking.
Before the worst could happen, the entire temple shimmered, then faded behind a stream of ghostly webbing. Kyrin had feared this--they got away clean, and could some day return--but the commoners cheered, simply for the great temple being gone.
They sieged each great house in turn, none defending any other's gates. House guards were slain, and many crusaders fell to magical traps, but few true battles took place. For the most part, each house's wards were systemically broken by mages, until the rabble could finally burst through the gates. The depraved acts the incensed commoners committed as they raided the houses, one can only guess. For the most part, all of the house leaders retreated long before their fortresses were broken, taking all of their most valuable possessions and most useful servants.
Days passed before the siege was fully complete, and weeks more before order was wholly restored. Shade claimed the city in the name of all free drow, and declared that she would keep the peace and defend the city until it was truly ready to stand on its own.
Meanwhile, the crusade began to fortify the city against inevitably counterattack, and tried to track down the retreating drow to cut them down before they could regain their strength. The war was far from over.