The knight standing before him was none other than Gascot. The very man who had fallen in battle against Ghislain had now been resurrected as a Death Knight.
At first, Gascot did not comprehend the situation. It was only after inspecting his body and the surroundings that he realized what had happened.
“This power of darkness… has turned me… into a Death Knight…?”
His voice, now deeper and more resonant than before, echoed ominously. His burning gaze made it clear—he was seething with rage.
“So, you really were a Black Mage… You used that energy you injected into me at the last moment… I wasn’t wrong…”
Rumble…
Gascot’s energy surged. His aura was even stronger than when he had reached the peak of his power in life.
Paradox
I’m sure the object from where Ghislain got the mana technique in his first life was developed by Astion. It’s a cycle, I don’t know exactly how it will work but I’m sure it’s like that.
Same with all the things he is changing to the future he knows, he thinks he is just making things faster but the original war where the saintess and Julian fought was probably also based on Ghislain action. Instead of reshaping the past he is just making it follow the one he already knows, even if he doesn’t realize.
I think this is what the author wants. Author wants to make everything in the future revolve around Ghislain's action from the past that made him do it in the future.
The same with the first time Jerome came out of the world and using the most basic spell (Magic Missile) that Ghislain's first action during his first time becoming a mage.
Also, I think Ghislain will be in the past for a very long time. Maybe around Astion being 9th circle is because Ghislain was still there doing everything and creating the Tower of Radiance.
personaly, i don't try to put a logic on a time travel that happen in a fantasy wolrd, or if it have to, i prefer the concept of new timeline created by the time travel
more please