Force lightning is a well known Force ability, most often used by practitioners of the Dark Side of the Force, especially the Sith. The ability is commonly referred to as Sith lightning, because of the usual users.
Force lightning is a purely offensive, energy-based attack that channeled Force energy down the user's limbs, hurling arcing bolts of electricity from the wielder's fingertips or palms; Force lightning could be executed with either one or two hands. Powerful discharges would branch out into dozens of smaller forks, thus skilled practitioners could target several foes at once.
The intensity varied based on a number of factors. A skilled user could render a target unconscious with only a short burst. A single, powerful blast was sufficient to kill a person instantly. Darth Bane's lightning, for example, would often electrocute his opponents to death on contact. The fact that it caused not only severe physical damage but also unbearable agony to the victim led to it being widely used as a form of torture, as when Darth Malak used it upon Bastila Shan, having captured her on board the Leviathan and having brought her to Lehon, where he converted her to the dark side.
Depending on the level of intensity, Force lightning could ground itself on an ignited lightsaber, with no apparent ill effect on the lightsaber's operation. Powerful light-siders were sometimes able to resist the attack, or even block the lightning completely. Force lightning could also be absorbed and redirected by a Jedi of sufficient skill; Revan demonstrated great proficiency in this ability; he used his bare hands to absorb a very powerful barrage of Force Lightning from Darth Nyriss and then deflected it back at her, destroying her with her own power in the process. There even existed an advanced version of Force lightning which may have been used by the Jedi Exile and Revan in the Jedi Civil War.
Effect of Force lightning
Though the short-term effects of Force lightning are obvious, the sheer power invoked by its use could have insidious long-term effects, both on those subjected to its power and those who would wield it. It deformed the person being shocked and it could also lead to them being crippled for the rest of their life; it was also known to cause brain damage and blindness.
Prolonged exposure to intense electrical fields (such as a sustained current of Force lightning) caused most humanoids to experience sudden and massive calcification of their skeletal system; the abrupt drop in blood minerals provoked muscular micro-seizures all over the victim's body. Intense enough doses of Force lightning will also result in the victim's skeletal system being seen through the body. However, this does not impact the user if it is redirected at him or her.
Telltale symptoms of this include generalized muscle aches and double vision; a blood test or bioscan could be used to confirm the diagnosis. Unless the victim received complete bed rest and appropriate medical treatment, the disorder would become chronic, lingering for years (barring timely bacta immersion). It was also thought that very intense use of Force lightning could drain the user physically, and possibly result in severe facial and body deformations. Besides draining the user's energy, Force lightning had the added drawback of occasionally charring the hand of the person who used it.
Use by Jedi
Force lightning ability is not restricted to dark siders. Jedi and other light-siders who were strong of will and character could learn this power without falling to the dark side but its use was viewed as inherently corrupting and most Jedi Councils forbade its use.
Some Jedi nonetheless refused to dismiss the natural power of this ability. During the Great Sith War, Jedi Master Lian Dray used Force lightning against the Sith apprentice Sindra. Revan, Meetra Surik, Jolee Bindo, Bastila Shan, and Vrook Lamar were amongst its users during the Mandalorian Wars, the Jedi Civil War and the First Jedi Purge.
Force lightning users
Force lightning required a living conduit for the energy to be channeled. Jorak Uln, the former headmaster of the Sith Academy on Korriban who hid in the Valley of the Dark Lords during the Jedi Civil War, would sometimes kidnap and torture Sith students. One of his favorite games was testing his captives on Sith philosophy, punishing their failure with Force lightning, often until they were killed. Darth Malak used Force lightning as a means of torture to turn Bastila Shan to the dark side. It was intended to give her a "taste" of the dark side's power, a technique that eventually succeeded. The Sith Emperor's Force Lightning was so powerful that he overwhelmed the Jedi Master Revan, to a degree that Revan's mask started to melt into his skin.
Variants of Force lightning
Force shock is a Force power that allowed the user to create an energy spark that would track and damage the nearest enemy. The shock could be thrown at an opponent to stun and injure them, or could be set loose to track an opponent until it dissipates. The shock would not last more than five seconds or so before disappearing into a tiny burst of heat, but it was a useful technique for Sith apprentices.
Force storm is a Force lightning variant. The user would raise his palm upward and would create, through the Force, an explosion of electrical energy directed at all foes in the vicinity. It also appeared as a tornado of energy which created a great disturbance in the Force. Jedi could also join together to create a Force storm, though its use was frowned upon by more orthodox Jedi. Unlike the Force lightning, Force storm was not limited to attacking enemies in one direction, as it affected all foes within a certain radius from the user. Some notable practitioners of this power were Revan, Darth Nyriss, Sith Emperor, Darth Bane, Galen Marek and Darth Sidious.
Chain lightning is a variation of Force lightning with the difference being that the lightning was able to strike one person and then move to another or several others. As it was more powerful than the standard lightning, it required a greater amount of discipline and concentration to project and sustain the stream of lightning. The only confirmed users are the Force apparition known as Dark Mara and Galen Marek and Count Dooku.
Sith barrage is a variant of Force lightning that allowed users to create a bolt of lightning up from the ground damaging anything in its way.
Lightning Shield is another variation of Force lightning in which a shield of lightning covered and protected the user. Its effects could extend beyond the immediate space near the user, and could shock enemies in the distance. It could lower damage taken by the user, and could also enhance the saber damage the user dealt out. It was not the most powerful form of Force lightning, however; it still took mastery in the art of Force lightning and high concentration to use Lightning Shield. It could even redirect Force lightning back at another user of Force lightning. The only known users were Emperor Palpatine and Galen Marek.
Lightning Grenade is a Force lightning variation in which the user gripped an opponent or object with the Force and lifted them up into the air. While the victim was suspended the user blasted them with a brief burst of lightning. The practitioner then either dropped the victim or slammed them into an object, causing the lightning coursing within them to explode. Galen Marek and Darth Sidious were the only known practitioners.
A powerful variation of Force lightning. The Force user blasted an opponent with lightning, and then, using the Force, caused the lightning to amplify within the victim's body until it reached a critical point and exploded out of the victim. The explosion would also shock and kill anyone unlucky enough to be standing near the victim when the explosion occurred.
Sith Seeker is a very uncontrollable form of Force push. The Force user blasted the target with Force push, sending the object through the air. The user then generated a large ball of Force lightning. The Force user allowed the lightning to expand freely, until it was no longer under his or her control. They would then blast the Force lightning ball after the target, hence "Sith Seeker". The lightning exploded on impact with an opponent or object. The only known practitioner of Sith Seeker was Galen Marek.
Lightning burst is a variant of Force lightning, where the user would have ligtning arc out from their body to strike adjacent enemies.
While most Force Lightning manifested itself as blue, it could appear in several hues, though whether or not the color is distinctive was unclear. For example, Palpatine, Darth Bane and Kallig had all used purple lightning. The Hidden One used white. Talzin and Mother were seen using green. Dark side users like Darth Desolous, Darth Tenebrous, The Son and Luke Skywalker were seen wielding red. Jaina Solo also used a highly unusual color variant, in the form of black.