In the battle for their lives (and everyone elses), Gourry tries to use the Sword of Light but it doesn't work against Ruby Eye Shabranigdu. Shabranigdu then attacks Gourry and Zelgadiss, leaving Lina all to Shabranigdu by herself.
Shabranigdu is about to attack Lina, but Zelgadiss stops him by calling Rezo who is still a part of Shabranigdu. Gourry then throws his Sword of Light, and Lina decides to use the Giga Slave. This spell, combined with the sword and with help from the Lord of Nightmares, is more powerful than the Dragon Slave.
She takes a swipe, but Shabranigdu blocks it. The Giga Slave went out of control. The darkness got wild, the chaos.. the Lord of Nightmares burned Gourry, Zelgadis, everybody. The entire world was tainted from that day on. Her magic burned itself out from the spell's power, drained from her. The Mazoku were overbalanced, they took over, feeding on the negative emotions they craved...She suffered for years without being able to hide or defend herself.