After a period of rest and study, the children of light descended the spiral staircase and returned to the black iron doors. Alec drew arcane runes around the doorway and soon the magical barricade and the massive doors shattered, revealing an ice cavern beyond. At the center of the room stood an altar, and Aten lay atop the unholy pedestal, each limb chained with black iron shackles. Two undead spirit devourers stood on either side of the altar; vile phantasms could be seen within their open ribcages. A massive crystal, pulsing with energy, hung above the dragonborn form. Four beams of necrotic power emanated from the gem, terminating in piles of corpses heaped at the corners of the icy room. A black throne rested against the far wall, and between it and the altar stood the lich Vecna, holding a staff and surrounded by a cloud of dark energy. As the party watched, the crystal pulsed and wrenched shimmering energy from the dragonborn on the altar. The gem then fed the power to the robed figure, and with a gesture he animated several skeletons and two viscera devourers – zombies with large, overextended tongues.
Seeing Aten shackled and subject to the deathly magic, the heroes attacked immediately. Ember used divine power to bolster her allies' defenses while Fas teleported the entire party close to the altar. Alec cursed the two spirit devourers before casting a spell on one of them that burned with radiant energy. Glace ran around the altar to Vecna and struck with his flail, teleporting both the avenger and the lich next to the altar. The other children of light focused their attacks on the undead lord now in their midst. Neri stepped forward and lashed out with her longsword, while Demarung swung his sword with a thunderous smash, knocking the lich and the two spirit devourers to the ground before taking on the war-form of the panther. Ember stepped away from the melee and released a wave of radiant astral energy, searing Vecna and one of his underlings. The lich stood and, as his wounds knitted together, claimed "It is too late. I have already ascended as a god!" The undead lord then tried to move away, but Glace and Neri lashed out to prevent his escape. The spirit devourers struck next, attempting to defend their lord. Glace dodged one attack, a bolt of necrotic energy, but the other devourer struck Neri with a lethal beam and the dragonborn disappeared. A heartbeat later, Neri's face appeared in the chest of the devourer as the creature began to consume her soul. The monster unleashed a surge of dark power, attempting to overwhelm Glace's mind, but the avenger resisted the attack. Meanwhile, the other devourer lashed out again at Demarung. The warden fought back, dealing his undead foe a grievous wound, but the flash of necrotic power struck the warden and he disappeared, his soul imprisoned in the devourer's chest. Aria sang a magical song to aid her allies' resistance to damage, quickly glimpsed into the future to aid an ally's attack, then summoned lightning that crackled around the weapons of the children of light. As her arcane tunes ended, the newly created undead rushed at the heroes from the four corners of the room. The viscera devourers attacked Glace and Fas; the avenger dodged the tongue that lashed out at him, but the invoker felt the cold claws dig into his flesh. As Fas tried to spin away from the attack, two skeletons closed in and tore at him as well. Two more skeletal warriors charged Alec, both slashing the warlock with their claws. Other undead rushed at Glace and Ember; both divine heroes avoided their deadly claws.
Ember had no sooner shrugged off the charge of two skeletons when an assault came from an unexpected source. An arc of unholy energy lashed at her from the great crystal, deadening her flesh and sapping a portion of her soul. As she recovered, Fas unleashed a searing wave of divine power, destroying two skeletons and inflicting holy damage on the devourers before vanishing and reappearing away from the crowd of undead. Alec focused a curse on the spirit devourer holding Neri and struck with radiant energy, forcing the monster to expel the dragonborn. The warlock then uttered another curse that wrenched the forms of Vecna and his skeletal minions. Glace continued his assault of the lich, tapping into Aria's glimpse of the future to blast the abomination with searing white light that charred his flesh and immobilized him. The shadar-kai then released a burst of radiance, instantly destroying two skeletons and withering burning two of the devourers. Meanwhile, Neri breathed a cloud of acid on the two devourers she faced and followed up with a swing of her sword before striking Vecna to draw his attention. On the other side of the altar, Demarung exerted a mighty effort of will to burst out of his captor's foul torso; he then leapt over his foe to threaten both the spirit devourer and Vecna, lashing out with his sword to deal the lich-lord a dire wound. Ember stepped toward the altar and summoned two bursts of radiant power in succession. One skeleton shattered, while both viscera devourers were charred as they were pushed back and stunned by the force of the divine energies. Vecna, seeing his underlings falling to the children of light, raised his staff to cast some unholy spell, but Glace took this moment to spring in and bash the lich with his icy flail. Vecna's putrid form shattered, his spirit screeching a promise of revenge as it dissipated into the cold air.
The undead lord's body was destroyed, but his followers fought on. Demarung and Neri again fell victim to the attacks of the spirit devourers, their souls absorbed into the monster's bodies. Aria attempted to free Neri by slashing at the devourer, but the creature's tough hide turned aside her sword. She then began a battle chant, adding arcane power to any attacks against her foe. A scream rose above the sounds of battle as the gem again drew upon Aten's vitality, channeling the energy to animate more skeletal warriors at the room's corners. The skeletons immediately charged. Glace deftly shifted to avoid the undead who rushed at him, and Ember's stout mail turned aside the hands grasping at her. From another corner, a skeleton charged at Aria and tore her with its cold claws while two of its allies slashed Alec. Fas also felt cold claws rend his flesh, but dodged a deadly arc of necrotic energy from the gem. The invoker then retreated from the undead surrounding him and summoned a stream of fire that engulfed one devourer before cascading onto the other, burning it badly and causing it to expel Demarung. The warden imbued his sword with the light of the sun and slashed, injuring and blinding his foe, then shifted to aid Ember. Glace summoned a spirit ally, and the shade moved to distract the nearest devourer while the avenger struck a crippling blow that freed Neri from her gruesome prison. Ember continued the assault by summoning a column of fire; another skeleton and the spirit devourer facing Neri both burst into flame and disintegrated.
Dodging undead enemies, Aria rushed to the altar to try to free Aten. The chains held him fast. Unable to free him, the bard healed him just before more of his life force was drained by the gem and channeled to the piles of corpses in the room, creating more skeletal warriors. A purplish-black arc of energy lanced down toward Aria, sapping her energy as the newly created skeletons charged the heroes. Two slashed through Ember's armor, and three surrounded Alec. The warlock teleported to safety, but not before his attackers clawed his arms and torso. Fas stepped away from the melee and blasted one of the viscera devourers with a bolt of blue energy that hurled it across the floor. Glace, meanwhile, rushed to the altar and lightly struck Aten, teleporting both himself and the dragonborn to Ember's side. The dwarf invoked a blast of white radiance that burned the nearby skeletons to ash but fortified Aten, healing some of his injuries.
Still fighting near the altar, Neri sliced into the remaining spirit devourer while the spirit summoned by Glace harried its flank. Nearby, Demarung whirled his sword overhead and released a storm of wind and lightning that shattered two skeletons and slammed into a viscera devourer. The warden then surged into a frenzy and slew two more skeletal warriors. The spirit devourer lashed out at Aria with its necrotic energy bolt. The bard's war-chants ceased as she disappeared into the monster's prison of bone. The creature then turned to the altar and egested his prey; Aria appeared on the shrine, chained as Aten had been. She looked upward and sung a dissonant strain, hoping to weaken the crystal, but the gem seemed unaffected and its dark beam descended upon her. She screamed as energy was ripped from her body and pulsed outward, and more skeletons rose with undead life. As the new enemies charged, Neri slew the viscera devourer she faced and spun to engage the spirit devourer. Skeletons closed in on the children of light, inflicting minor injuries on both Fas and Glace. The invoker shouted a divine curse of doom that dazed the nearby undead, while Glace charged the spirit devourer that hovered near Aria's shackled form. The avenger's icy flail lashed out three times, and the abomination fell. Neri slew the final devourer, and she and Glace attempted to free the bard. As Demarung and Ember engaged the skeletal warriors with primal and divine energy, Glace told Aria to strike him. She did, and the shadar-kai teleported them both away from the unholy shrine. Only two skeletons remained standing. Alec slew one with a bolt of dark, crackling energy; the last fell to radiant blades summoned by the eladrin invoker.
The heroes paused for breath, still ready for any threat. However, the attacks ceased. The necrotic jewel, deprived of a victim to serve as a source of life force, ceased to animate new undead warriors. The group focused their collective will and sensed no presence in this realm opposed to them. They merged the world of chilly air and clouds with the civilized lands, bringing a new sky to the lands they had formed.
Upon returning to lands of the elves and eladrin, the children of light found that centuries had passed since their last visit. New leaders now governed the fey folk, and dissension and conflict afflicted the realm. Two hundred years ago, a group of secretive elves living underground had been forced to the surface by horrors from the far realms. They had settled on the edges of elven and eladrin society. Soon thereafter, allegations and rumors began to circulate – accusations that the subterranean elves had tricked or tempted other fey folk into participating in dark magic and the worship of evil. They claimed that they taught only those who came to them with a desire to learn their style of magic and worship. The leaders of the surface fey folk had gathered to counsel among themselves about the subterranean elves' influence. The children of light approached the council chambers, sensing a great magic being wrought by those gathered within. Guards stood outside the room, barring entry and telling the children of light that the fey leadership had prepared a spell to mark the subterranean elves as a warning to others to avoid their dark ways. Neri and Alec forced their way into the room, opposed to any actions taken against the accused. Glace also teleported in, angered by the hubris of the council, regardless of the subterranean elves' actions. A moment after the children of light entered the room, the Summer Queen drew power from Fas, who supported the decision, and the spell was finished. The skin of the entire race of the subterranean elves, and that of Alec, their patron, darkened to an inky black color, while their hair faded to pure white.