A dark energy trap was a dark-side Force power, conjured through Sith magic by a Sith sorcerer. Dark energy traps resulted from intense concentrations of dark-side power. To a trained eye, they appeared as faint shimmers of purple in the air and, under the Sith practitioner's spell, could immobilize even a skilled Force-sensitive being for a time. They could, on the other hand, indefinitely entrap a being who was unskilled.
In 23 BBY, Darth Tyranus employed dark energy traps against the Jedi Order coalition team sent to Korriban to track down galactic criminals Granta Omega and Jenna Zan Arbor. As the eight-member Jedi team entered the Valley of the Dark Lords, assaulting them on all sides were waves of darkness, the oppressive effects of which required great effort to wade through and overcome. Entering the Valley's ancient mausoleums, the Jedi were simultaneously assaulted by dark-wave whispers and corpse visions amidst the tombs of the Sith Lords. The traps were set by the Sith Lord Darth Tyranus in an effort to fend off the Jedi intrusion into the Valley, where he planned to rendezvous with Omega and Zan Arbor, to establish an "alliance" with them.
While the Jedi survived their encounter with an undead platoon of Korriban zombies and, with Master Obi-Wan Kenobi's advance warning, stayed clear of the dark energy traps, Padawan Anakin Skywalker was not so fortunate. Although he overcame the zombies, Skywalker—racing after his Master, who was pursuing Omega and Zan Arbor—blundered into an energy trap, which immobilized him for a time. Frustrated and enraged, he slashed at the invisible cage with his lightsaber, but could not free himself. Skywalker then kicked and hammered at the energy walls, to no avail—altogether astonished that he had encountered a power greater than his own. Anakin attempted to call out to his Master, but his voice was silenced as it was sucked out of the air and imprisoned by the energy trap; even if Kenobi had been close, he would have been unable to hear his ensnared Padawan. Moreover, Skywalker's own visions of what had just happened to his dear friend Darra Thel-Tanis (who had been shot and fatally wounded by Omega) got in the way of his accessing the Force to free himself. But eventually, the prodigiously Force-talented Skywalker managed, like a Jedi Master, to remove himself from the energy trap on his own—a feat which greatly impressed his Master.
- The Complete Star Wars Encyclopedia