Eclipse of Umbara

"You have to let go of your tethers. You have to plunge into the Force itself, without Light or Dark, ready to die for the cause you fight for. You give yourself entirely, and you receive true power in return."

- Talzin to Ganner Slarwalker during the battle.

The  was the final battle of the Shadow Conflict. Though the rest of the conflict had been kept mostly confined to a few combatants at most, the eclipse saw two full-fleged armies go to battle, and was by far the most destructive battle of the conflict. It saw the defeat of the Shadow Assassins, Ganner Slarwalker's departure from the, and the return of Darth Massikus, with lasting effects on the galaxy.

Prelude
After springing a trap on Antimatter Squadron and Ganner Slarwalker, Arek Saris and Siri Tokolighter returned to the Umbaran Sith Academy with Captain Xux and 49 other Death Watch mercenaries. To ensure that Xux was the warrior he wanted, Varad Zagg ordered the fifty mercenaries to fight to the death. Much to his satisfaction, Xux won, proving himself ready for The Binding, as well as a second ritual to amplify his connection to the Force. Shortly after, Talzin returned to Umbara with Yula Ardinn.

At the same time, Ranulph Darkhitch and Hans Novastar contacted Dylan Antiunknown and made a deal with him, agreeing to give him every lightsaber from the Shadow Assassins to sell in exchange for medical aid for Ganner Slarwalker and support in the battle. They made their way to Umbara aboard the Brotherhood HQ.

Sometime just before the battle, Talzin resurrected Darth Massikus in secret. He told her that he was visited by his apprentice in the afterlife and show mysterious visions of the future. Determined to understand more, Massikus prepared to leave.

The battle
Ganner and the troops landed on the now-abandoned Umbaran airfield, establishing a staging point for their assault on the Temple. Under orders from Saris, Shadow Assassins began to surround the airfield, but as they began to attack, Varad sliced into Brotherhood communications and ordered the activation of Eclipse Protocol. The Brotherhood HQ targeted the airfield and fired its experimental superlaser, causing heavy casualties on both sides, though Ganner, Hans, and Ranulph all survived.

Knocked unconscious by the blast, Ganner was visited by visions of Talzin, where she revealed to him that the ritual that would be used on Xux had also secretly been used on him when she had bound Darth Massikus to him in preparation for Ganner to defeat the Shadow Assassins. Talzin explained that she had seen a future where Varad succeeded in his plans and destroyed the Galaxy, and sought to avert it, thus choosing to set Ganner up as her secret weapon to destroy Varad when his guard was down. Talzin urged Ganner to let go of the Jedi Code to fully embrace his power, and as the vision ended, Ganner ultimately choose to do so, awakening as Massikus left Umbara.

By this time, the Assassins had regrouped at the temple and the Brotherhood had began to retreat, but Ganner pressed on, single-handedly defeating Siri and the majority of the remaining Sith at the entrance while they bought time for Varad to perform the Binding on Xux, bringing back Darth Ruin in his body. However, Ruin turned out to be mad and ran away at the earliest opportunity, taking Varad's shuttle and heading to Korriban.

Breaching the temple, Ganner fought his way to Saris and Varad, flanked by the remaining Shadow Assassins who tried to utilize to win, but ultimately Ganner overpowered them all regardless. At last, in a final two-on-one duel, Ganner held nothing back, killing Saris by stabbing backwards at him, and beheading Varad. The Shadow Assassins had been defeated.

Aftermath
Ganner, Hans, and Ranulph escaped the aftermath as soon as possible, hoping to return to Coruscant and leave the Brotherhood behind. However, they didn't know that Dylan himself was also on his way to Coruscant, seeking revenge.