We all know the first line of a query is your "hook." I call the last line the "sinker." You want it to punch them in the face, in a nice, friendly kind of way that makes them unable to forget you after having read the 300 other queries in their inbox.
If you're looking for query advice, but are slightly intimidated by my claws, blade, or just my rolling googly-eyes, check out the query critique boards over at AgentQueryConnect. This is where I got my start, with advice from people smarter than me. Don't be afraid to ask for help with the most critical first step of your writing journey - the query. My comments appear in green.
In a land ruined by war, seventeen-year-old Aurel Tritten knows the greatest casualties come the day the sky turns emerald. Every year, at the exact same time, mothers disappear from their homes, soldiers from their barracks and kings from their castles. She's been told since childhood the emerald sky takes people to a happier place, the City of El, where there are crystal palaces and colors brighter than a rainbow, but Aurel thinks there's an equally good chance they're dead. I'm into this so far!
When the sky shifts to green like it does has? every other year I'd rephrase b/c "every other" makes it sound like a bi-annual event, even though I don't think that's what you mean, Aurel
Aurel's identified as Nissa, the once-revered Gold Sentinel and prime suspect behind the latest tragedy of war. The sentinel stands accused of opening the barrier and letting in the shadow monsters for a bloody feast Aha - there's some answers here for my earlier question, but I'd clarify in the above para that there are in fact monsters present. Aurel is imprisoned for Nissa's crimes. Her only escape is proving Nissa's innocence by remembering what really happened, but with each memory, Aurel drowns deeper in the other girl's life. If Aurel can't unlock the secrets in her mind and identify the true traitor, she’ll be the death of an entire world. If she does, and Nissa was truly wicked, she'll be the death of herself.
HER EMERALD CHAINS is a young adult high fantasy complete at 83,000 words.
Barring my above comments, this looks really great! Polish up those little nits and you're ready to query.