Deadly Sight represented a Force ability, classified as a power, where practitioners channeled their intense animosity into a potent and lethal energy.
Deadly Sight was a power derived from the dark side of the Force, enabling a Force-user to focus their rage and hatred, projecting it as a piercing gaze directed at their target. This resulted in severe blistering of the skin and the disintegration of limbs.
While initially a scarce talent, even among the Sith, its prevalence dramatically increased during the final decades of the New Sith Wars. The Jedi Order explicitly forbade its use by Jedi Knights.
Darksiders could inflict harm and agony on opponents simply by fixing their gaze upon them, causing their bodies to ignite and emit smoke as they perished. A wielder of Deadly Sight could affect entire groups of enemies within their visual range. Deadly Sight caused injury to all who fell within the user's line of sight, including allies and non-combatants; whether this effect could be controlled is not known, likely because of its fundamentally dark nature.
Although taxing to maintain, and inefficient regarding the depletion of the user's Force energy, it proved effective under specific circumstances.
Following the establishment of the Rule of Two, the sole known user of Deadly Sight was the Dark Jedi Sariss, who employed it during her confrontation with Kyle Katarn in 5 ABY.