Here's the letter:
(Why you are querying) I'm sure you meant to move this line down here, but just to be sure. Also, I've said many times I prefer personalization at the end, so I won't harp on it any longer.
Seventeen-year-old Mihael This is a weird spelling, but I see from the rest of the query it's on purpose. Wrath This name feels a little too obvious to me, but that's not really query critique territory. is the son of the most powerful Sin in the Demon Realm, but if he doesn’t turn into a full demon by his eighteenth birthday, he’ll be just another blood splatter on the sacrificial altar.
Okay. I like this. I have no idea what a Sin is, or how turning into a full demon works, but it doesn't really matter, because this is just the hook. I'm hoping we get an idea what Mihael is before becoming a full demon (half-demon? no-demon?), but I'm sure you'll get to that.
With his crucial birthday looming and not even a demonic roar inside him, See? I knew we could count on you. No-demon it is. Mihael discovers his father’s plans to launch the Apocalypse and make the AntiChrist rise, with Mihael’s split You really mean split, not spilled, right? blood being a key part of that plan.
I think you need to clarify what you mean here. You mention Mihael being murdered in the opening hook, but then this paragraph confuses it. Is he some kind of demon-human hybrid? If so, you need to say so. If not, you need to explain what he is.
With brains, guile, and a powerful aid, Like another character? This is vague. Mihael escapes from his father’s demonic clutches. His only hope lies in the human world, in his new allies(, Oxford comma) and the answers he’ll find there. He joins up with an unstable psychic and her half-angel friend, who he finds are also being hunted by his father,
With few clues to guide them, Mihael and his friends must find a way to fight back against
HALF-BREEDS AND OTHER LIABILITIES is a 80,000 word YA Urban Fantasy novel that will appeal to fans of Holly Black’s
Thank you for your time.
Okay. You're off to a good start here. You've got some cool elements, and you certainly cover a clear conflict, and imply a decent choice, but you need to focus this query more. Avoid vague-ness, and focus on specificity.
Also, I get that his father is Wrath, and that Mihael shares his surname, but I would suggest keeping that out of the query. It would just confuse things.
What do you all think?