Heading north to Dark Eden, Kain discovered the realm a ruined wasteland filled with lava and ruined villages and dominated by a dome of energy that mutated the lifeforms within.
Travelling to the north of the area Kain discovered the source of the dome - a tall tower spewing radiation from its top. Entering the castle Kain discovered its warped interior dimensions and battled his way through, making his way through two different dungeon routes containing the Flesh Armor and the Spirit Deathspell before making his way to the top of the tower where he confronted those responsible and finding that the Circle of NineBane, DeJoule and Anarcrothe had worked together as a group to cause the mutations of Dark Eden.
As Kain attempted to confront the guardians, Anarcrothe summoned Malek to their aid and fled, while Kain responded in kind - using Vorador's Signet Ring to summon Vorador. While Vorador and Malek reignited their ancient fued, Kain followed Bane and Dejoule outside where he confronted anddefeated them both. Returning to the castle Kain discovered the broken armor of Malek - proof that Vorador had laid his old adversary to rest.
The fate of the castle - along with the rest of Dark Eden is unclear. It is unknown if Kain's path through the castle resulted in the deactivation of the mutating influence being projected - although it will still be present if Kain returns to the area. Ultimately it is unclear if the expansion was halted but it is never mentioned again in the main series. Background materials to the cancelled multiplayer Nosgoth suggested that the dome of energy had indeed been deactivated and the direct mutations stopped, however the fallout of the incident continued to affect the area as it seeped into soil and water tables, gradually effecting the humans that lived there - although not causing the same physical deformities.