Gebelk was tasked with finding the best way to strengthened the ka of the prisoners, captured during the ka hunt. In the underground prison, he conducted experiments on the prisoners, where he discovered that hunger and fear were the best stimulants to bring out the ka's violence. He also tried torturing the prisoners, but found it counterproductive since it killed their ba. He concluded that the wielder's desire to live was what made their ka strong and the best way to bring this out was to have the prisoners battle each other to the death for survival.
Gebelk had an arena set up and put ten prisoners inside it. They were given one rule; only one of them may leave the arena alive. Over the course of 34 hours, the prisoners engaged on and off in fights, using their ka. The ka were small and weak at the beginning, but grew in strength and size, as their hosts fought to stay alive.
The last two surviving prisoners had the ka, Five-Eyed Horned Ogre and Gudoul. When Seto checked in on the progress of the progress of Gebelk's research, he saw these two fighting and was impressed by the power of their ka.
|Prisoner||Five-Eyed Horned Ogre|
- ↑ 1.0 1.1 1.2 Yu-Gi-Oh! Millennium World Duel 31: "Ripples in the Shadows"
- ↑ Yu-Gi-Oh! Millennium World Duel 32: "The White Dragon Awakes!"
- ↑ Yu-Gi-Oh! Millennium World Duel 33: "The Vessel of the White Dragon"