Long ago, Nibel the Lord of Light and Encablossa the Lord of Darkness made a pact: each would rule his age and yield to the other in turn. When Nibel's era ended, he refused, and Encablossa unleashed his Dark Legion in retaliation. Ages later, in Kingdom Under Fire: Crusaders, the ancient heart relic was shattered by Walter's soldiers and Encablossa manifested as a colossal demon — defeated by the combined forces of Kendal and Regnier, who were then trapped inside Encablossa's dimension, aged and diminished. Regnier's campaign reveals the darker truth: the dark dimension itself is on the verge of catastrophic collapse, a detonation that would consume both planes of existence.