Well, if my research vacation is over then you all get to suffer with me and read my notes.
Back in May, Travance unlocked the door in the Pale Keep, releasing 12 Death Knights out into the world.
In August, Travance was visited by the first of these Death Knights, calling itself the "Tempest Hunter".
This one emanated aberrant chaotic energy as well as aberrant light energy.
It had small eidolons with it that were weak to a variety of energies--when these were slain, they expelled a burst of chaos that attempted to alter everyone around them. If successful, the eidolon soul entered that person, and when the Travancian was slain, a burst of red energy resurrected the Eidolon.
The Death Knight also tried to turn Kanas into an Eidolon when he died near it.
When the Knight dropped, we saw its soul, but energy of an aberrant chaotic nature (specifically red crackling energy--the Crimson Mantle, most likely) yanked its soul away, with the sense that it was still captured.
This red energy that we've seen emanating from the Knight and the eidolons fits with a power(?) originally found in the Pale Keep, the Crimson Mantle. Back in May, Travance stopped Alverez's cronies fom attempting to obtain this power source.
I am not sure what exactly the Crimson Mantle is and how exactly it connects to/interacts with the Death Knights--if anyone else has more information, please share!
One fact we do know is that all of the Death Knights have something red on their person, whether that be a scarf, cape, cloak, etc.
We have confirmed there are 12 Death Knights, and each one of them aligns with a Constellation in the Kormyrian Zodiac.
When in the Pale Keep, Mae Fang recovered 12 statuettes of Death Knights. After the fight, a constellation lit up red on one statue.
This Death Knight called itself the Tempest Hunter, and appropriately, the statue matched the sign of the constellation Aashirya.
Upon further investigation, all 12 of these statues have zodiac symbols on them.
I did not have the opportunity to engage the Death Knight for long, and was not present when it dissipated. If anyone else has further information on the Death Knights, Pale Keep, Crimson Mantle, or anything related to these topics, please share what you know!
I will also be at the Winterdark Ball with my notes, and am willing to sit and discuss then as well.