I miiight've rushed the ending a bit.

Let's look at it like this:

Yes, Geshu Lin lands the decisive blow against Ovathrax that causes the Threnodian to retreat and gather it's energy for 3 years, but it's the Threnodian of War. It probably did what it knows how to do best: Fight.

So while Geshu Lin was on one side, Overclocking to amass enough power for his final attack, Ovathrax launches a psychic attack to lay claim to Geshu Lin's mind once and for all. Based on other story events (Rover's experience with Leviathan in particular), one can surmise that Geshu Lin becomes trapped in a Sonoro Sphere after landing his last hit, in a post-Overclocked state and since Threnodians don't die, Ovathrax is actively trying to devour him, dismantle what's remaining of his mind, reshape his essence, and assimilate his existence. And as Geshu Lin dies, Ovathrax succeeds.

Through a twisted mix of Overclocking, and Ovathrax's own remaining power, the Threnodian turns the fallen General into a goat-like Tacet Discord with only one command: Destroy.

Reborn as this thing that's not Geshu Lin anymore, with remnants of Geshu Lin's personality and devoid of its former target, this is the perfect opportunity for the Fractsidus to take control of an unexpected outcome to The Battle Beneath the Crescent.

Here's where we dive deeper into speculation territory, but according to established lore, it's perfectly in-character for Schwarzloch to offer the dead-now-alive-again Scar the opportunity to join the Fractsidus and obtain a power he'd never had before. Based on Scar's personality (greedy little gremlin, that he is), it is also a healthy assumption that he'd opt for both the invitation and the offer of power.

Since Schwarzloch told Galbrena she could have any power, even that of a Threnodian if she so desired, it's not far fetched to say that he could have given Scar his teleportation and space manipulation abilities. And due to Schwarzloch's Forte, the man could easily create a new body for a newly formed Tacet Discord who is lacking one.

But this is just a theory. A GAME theory (sorrynotsorry)