In Blood Omen, DeJoule (also written as Dejoule) was the Guardian of the Pillar of Energy. Her magical talent was in gathering and directing energy for her own purposes.
The power DeJoule wielded had affected her body over the years, altering her physical form. Her body glowed brightly, 'with an intense blue light, constantly caressed by tongues of flickering energy'. This aura could be very harmful to those who ventured too close to her. It could blister skin and sterilize cells.¹ To contain her power, DeJoule wore a heavy Insulating Robe, made of a dense alloy. This piece of unused Blood Omen dialogue suggests that even her fellow Guardians were not safe from the dangerous energy field:
"The cloak's lining was scorched and melted. It served as an insulator, made to protect DeJoule's colleagues from her deadly radiance, lest it char and burn them to withered, smouldering husks."
After Ariel's murder and the corruption of the Circle, DeJoule worked with Bane and Anarcrothe at Dark Eden. All three were tainted by Nupraptor's insanity. Approaching the area, Kain saw that their combined magic was twisting the land around Dark Eden's tower, causing mutations of plants, humans and beasts. Eventually, all of Nosgoth would have been engulfed by their growing dome of sorcery, spewing from the tower's apex.
Kain found the three Guardians in the tower, but Anarcrothe called upon Malek and then vanished. Kain responded by summoning Vorador to assist him against the Paladin, then chased Bane and DeJoule as they escaped outside. He was forced to fight them both at once, in an open-air area containing water and earth.
During the battle, DeJoule discarded her robe and further defended herself by standing in the body of water. She also summoned spheres of energy to act as shields while she fired energy bolts at Kain. It was not enough to save her, however. When Kain killed her, he claimed her Insulating Robe and returned it to the Pillars.