The plans for the Scourge War had failed, and Kel'Thuzad had fallen into the Maw alongside Arthas.
In this wicked place where shadows converged, only Arthas's soul had received special treatment. Every other soul that entered the Maw was swept into the River of Tormented Souls by the chaotic countercurrents.
Kel'Thuzad struggled in the River of Souls, trying to find a way out, but the boundless gray-white mist obscured everything.
Within the wind-whipped River of Souls, there was nothing but cries of agony and the heavy panting of his own soul.
Of course, souls had no need to breathe. That heavy panting was the sound of terror produced as a soul was stripped apart.
But Kel'Thuzad had never resigned himself to his fate. After seeing through the lies of the Lich King Ner'zhul, he had resolved to seize power through his own will.
Soon, Kel'Thuzad discovered scattered Tormented Souls in the River of Souls. Drawing on his relatively powerful soul, he devoured the drifting souls one by one.
Devouring souls meant capturing anima.
Kel'Thuzad discovered this unique source of energy. Using anima, he gradually rebuilt his body, then found the spiritual consciousness of a twisted monster in the River of Souls and unlocked anima sight.
Once he could see, Kel'Thuzad worked out the direction of the River of Souls' current. After wandering through two cycles of light and shadow in the sky, he found a way out.
Kel'Thuzad emerged from the River of Souls, only to discover an unfamiliar being waiting for him.
The tall royal figure, dressed in lavish clothing, sealed his soul form inside a vessel filled with grim veil.
Everything went black. When Kel'Thuzad regained awareness, he was already inside a noble's castle cast in gloomy hues.
A gaunt Venthyr noble threw Kel'Thuzad into an underground cavern