Great first chapter, keep it up

7719306 Thank you kindly ^^

Interesting, but yeah, despite bad past experiences with it, time travel would have been the more efficient chose than waiting thousands of years and hoping that, if and when Trixie is reborn, Starlight will be able to find her. Plus, unlike last time, the time travel would only bea month or two into the past tops; far less risky.
Oh well, suspension of disbelief suffering a minor blow, I'm still curios enough to read on.

7721110
Come to think of it, didn't the spell Starlight used to change time get destroyed? The only other time spell we know of is the one Twilight used once, and we know that one just ended up making Twilight the cause of the very thing she wanted to avoid.

So, I guess it makes a lot of sense Starlight doesn't use a time spell.

(Too bad we didn't think of that. )

7721236
First, I don't really care that time-travel isn't in this; it's not that sort of story, after all, I'm just saying it's hard to beleive that this was the plan she came up with as the best way to be reunited with Trixie. Seems like this would be plan Z, not A.
There are plenty of ways to address the time stuff, though I don't think just saying that, since that spell on the paper was destroyed, it is now impossible for anypony to go back in time in a similar fashion, is the best way to do so.
The idea that Starlight, probably the most skilled mage alive, capable of defeating the Princess of Friendship easily over and over, who could put Starswirl to shame if she applied herself, couldn't create a new time-travel spell from memory that functioned at least well enough to go back the significantly shorter amount of time required to keep Trixie from getting her neck snapped is kind of hard to swallow.
That being said, there are ways to explain it better, like, in the time it takes her to make a new spell, years have passed and the world has been threatened and saved multiple times, time travel then would invoke that fear that it could doom Equestria. A few months is probably not going to break the world, but a decade might.
A great reason to explain why time travel isn't an option isn't required for a Lich-Glimmer to be a thing, but it would help.

P.S.
One of these days, the show's gonna have to do a flashback episode all about Celestia, Luna, and Starswirl so we can actually gauge what he's capable of and if it surpasses Starlight Glimmer's already impressive resume.
I imagine he's not as good as modern unicorns, but his work was instrumental in causing that. Like, he was the best unicorn of his age that spent his entire life making new discoveries and progressing magical understanding so that foals of the future could learn his life's work in a couple years of classes and then build off of it.
This is true in real life; the average high school graduate knows more about science then the best scientists from hundreds of years ago.