Sagu, after recovering from his weakness, vowed the downfall of Koguryo and the death of King Yuri. Through his mysterious dark powers, the warlock worked his magic and crafted a Darkchild; a vile creature of terrible destruction.
Darkchild called forth evil creatures to invade Koguryo. The streets were overrun with diseased rats; desacrated warriors within the lands returned to an unholy life, feeding upon the lives of the mortal. King Yuri sent his desperate men to search out the Darkchild and destroy it wherever it might lurk. There were even traitorous citizens amongst the invaders, swathed in dark clothing, the colour of Sagu's heart. Yuri forbade any loyal Kogurian to wear black during this time, as they might be mistaken for the enemy. With a reward of gold being offered to the heroes who vanquished the source of evil, many brave Kogurians fought to the death, defending their kingdom.
Seeing his cause was defeated by so many men and women of the kingdom who fought with such valour, Sagu returned to the Darkchild, tormenting those in King Yuri's envoy who attempted to destroy it. Yuri sent M'hul to meet up with the heroes Cable, WinZip, and many others to destroy the vile creature. The death of his finest creation struck a hard blow to Sagu, who, broken and defeated, retreated back into the shadows from whence he came, licking his wounds to return for the vengeance that ate at his soul.