This dark side entity appeared in a vision to a young Anakin Skywalker during his training as a Padawan in the Jedi Temple.
The dark side entity appears in front of Anakin Skywalker
Sometime after the Battle of Naboo, during a lesson with Jedi Master Tera Sinube in the Jedi Temple on Coruscant, the young Padawan Anakin Skywalker sensed being choked by something he could not see.
That night, feeling a disturbance in the Force, Skywalker left his dormitory and went to the Jedi Council Chamber, where this dark side entity appeared in front of him. Activating his lightsaber, Skywalker engaged the entity in a lightsaber duel and questioned it on its motives. The entity then told him that he would turn to the dark side of the Force.
The dark side entity battles Anakin
Foreshadowing his future attack on the Jedi Temple, a group of defenseless younglings materialized in the Jedi Council Chamber. The entity told Skywalker that he could not save them, and that their fate was already sealed. The entity then subjected him to Force lightning. As he was losing all hope, Skywalker intuitively used telepathy to call out to Padmé Amidala, who heard his desperate plea far across the galaxy, on the planet Naboo. Focusing on his close friend, Skywalker filled up with energy of the light side of the Force and destroyed the entity.
Following the incident, Jedi Knight Obi-Wan Kenobi, warned by Tiplee, found his apprentice in the Jedi Council Chamber. The exhausted Padawan was then taken to his room, where he fell asleep. In the corridor, Grand Master Yoda explained to Kenobi that Skywalker had experienced a powerful vision and that perhaps, in time, they would understand it.
The dark side entity is destroyed by Anakin Skywalker's use of the light side of the Force
This dark side entity wielded a red-bladed lightsaber. It was skilled in Force choke and Force lightning, two abilities mostly used by practitioners of the dark side of the Force. It also proved to be impervious to Anakin Skywalker's attacks while he was in a state of anger. However, the entity disappeared when Skywalker employed the light side after reaching out to Padmé Amidala by telepathy.
This dark side entity first appeared in Temple of Phantoms, a comic written by Christopher Cooper and illustrated by Bob Molesworth, which was published in 2014 in Star Wars Comic 9.