Summary
The Final Mission arc is the endgame confrontation at the Final Station, where the hidden rulers of Berkav, Thespara, and Orbos are finally gathered into one late gate-war reckoning. *1 *2
After Sarhanna falls, the surviving trail points back toward Vinerel and the hidden route beneath Vantinoria. The crew learns that the portal to the Final Station lies under his castle and uses that discovery to force its way into the last stage of the story. *3 *1
Beyond the portal waits a massive station over an unknown world, with Vinerel receiving the crew beside Sarhanna and Lindor. The corrupted gates, the old gate-cleansing sacrifice, and the successor project aboard the Phantom Epoch all converge there into one endgame thread. *2
SpoilerOrbos-12
The portal beneath the castle is confirmed, and the crew uses the route under Vantinoria to reach the Final Station. *3
SpoilerPhantom Epoch Extras 32 / 36
At the Final Station, Vinerel explains that Sarhanna and Lindor led the desperate gate defense, that the Vanished gathered around the corrupted network to carry out the cleansing at the cost of their lives, and that he built the Phantom Epoch contingency in case the defenders were lost. *2
SpoilerPhantom Epoch Extras 33
Lindor dies at the station and his body fades from sight, showing that the Thesparan ruler's end is part of the same Vanished-era collapse revealed at Final Station. *4
SpoilerPhantom Epoch Extras 34
Sarhanna dies and begins to fade from existence, confirming that Berkav's ruler is caught in the same Vanished-era collapse. *5
The endgame is closely tied to the Final Station, the Vanished sacrifice described in Gate Cleansing, and the final collapse of the hidden ruler network through the deaths of Lindor and Sarhanna.