Battle of Nelvaan

"Anakin. Though you've never had the official Trials, this war has tested you more than the Trials could. Save one. Master Yoda foresaw this. The Force has guided us here for your final Trial. The one you have never truly faced." "Master. I haven't always been a patient student. But I have proven myself. I am a Jedi Knight. I won't fail you." "No, Anakin. Don't fail yourself. May the Force be with you."

- Obi-Wan Kenobi and Anakin Skywalker

The Battle of Nelvaan took place in the year 19 BBY. Nelvaan warriors were being experimented on by the Techno Union prompting Anakin Skywalker to aid in their uprising.

Prelude
Following the siege of a rain-soaked planet occupied by the Confederacy of Independent Systems, High Jedi General Obi-Wan Kenobi and Jedi General Anakin Skywalker were contacted by Supreme Chancellor Palpatine and Jedi Master Mace Windu to investigate the Outer Rim world of Nelvaan after word supplied from Republic Intelligence indicated that General Grievous was currently stationed there. Departing immediately, Skywalker and Kenobi arrived at the planet via their Star Destroyer Integrity. A clone trooper informed Skywalker and Kenobi that no enemy forces were detected on the planet, save for a number of strange geothermal readings. Deciding that the readings were worth investigation, Skywalker, Kenobi, and a small force of clone troopers landed on the planet's surface via CR-20 troop carrier.

Battles
While investigating, Kenobi and Skywalker were suddenly ambushed by a massive Horax, which Skywalker made short work of with the help of his lightsaber. However, a group of Nelvaanians appeared in the wake of the beast's death, and he and Kenobi were then escorted to the tribe's village, Rokrul, where they met with the village shaman Orvos. He revealed that Skywalker's killing of the Horax interrupted a young Nelvaanian's rite of passage trial, and also told of how the Nelvaanian adult males, each of whom embarked on similar quests, disappeared from their village, with only the "Ghost Hand" as a means of rescue. After Kenobi presented Skywalker's prosthetic arm to the villagers, they realized that he himself was the "Ghost Hand". He then underwent a trial where bruise-leech crawlers left geometric tracks over his body, and, the next morning, began his long journey to save the village and uncover why Nelvaan was shrouded in seemingly eternal winter and to find the missing Nelvaanian warriors—this was the final Jedi Trial Skywalker had yet to face.

Following the Force, Skywalker uncovered a cave in the midst of a blizzard, where he experienced a vision of a Nelvaanian becoming mad with power; this was a prophecy of Skywalker's future as Darth Vader. Once he snapped out of his vision, Skywalker uncovered a CIS base containing a siphon generator that was powered by a geothermal crystal and kept the planet in its wintry state. A group of Skakoan combat engineers were stationed at the base, creating mutant Nelvaanians at the request of Grievous. Harvos, the only Nelvaanian captive who had yet to be altered, was placed in a tank and immersed in green liquid, slowly mutating him, but he managed to break free and assisted the young Jedi in freeing the mutant Nelvaanians. Skywalker then scaled the siphon generator and destroyed the crystal powering it, risking damage to his prosthetic arm in the process. As the planet's ice age came to a close, Skywalker clambered to the surface, killing off the Skakoans and their leader in the process. After Skywalker returned the Nelvaanian males to Rokrul, he and Kenobi departed the planet in the Integrity.

Aftermath
Following these events, Kenobi and Skywalker left the planet to a MedStar-class frigate orbiting the planet Belderone, where they resided for four days to check on their Twi'lek captive Fa'ale Leh. Onboard the frigate, Kenobi received a transmission from Jedi Masters Mace Windu and Yoda as well as Supreme Chancellor Palpatine, in which he was informed of CIS Count Dooku's location on the planet Tythe. Though Skywalker was reluctant to continue being separated from his wife Padmé Amidala, he nevertheless joined his former Master in the search. However, little did they know that the battle was a diversion by Palpatine (under the guise of Darth Sidious) to keep them away from the Core Worlds in advance of the massive Separatist invasion of Coruscant.