Yeah, there's definitely too much going on with this. It's hard to keep track of all the pieces. Simplify. Plus, this reads more like a log line than a hook, and, yes, it's a fairly generic fantasy hook. Not to mention that it's honestly too vague to tell me anything. I don't know what a keeper or a seeker are in this context, or what any of the last portion means. I can't even tell if the Last Army of Men is with the good guys or bad guys.
If I were you, I'd attack it from a different angle. Pick one of the characters to focus on. Even if your story has multiple POVs, pick just the one character who it is most about. Then focus the hook on them. What's the inciting incident for them? For instance, while obviously taking great liberties of what your story is, let's say that ultimately the hero of the story is the prince, whose name is now Herbert, and the story starts when assassins come after him. So, your hook could look something more like this: "After narrowly escaping an assassination attempt during the midwinter festival, Prince Herbert discovers this was just the first step of a war for dominion over the world." Or maybe you decide that you're best served by focusing on Carlos the seer, who had a premonition of the world in ruins and sets out to save it. Or it's best to focus on Susan the keeper, who has been in jail but is now being released because they realize she's the only one who has some requisite skill to save them. The point is, pick one character, and use the hook to introduce that character and the initial challenge facing them.
Now, you don't absolutely HAVE to use the inciting incident as your hook, but it's a good place to start anyway. But do focus on one character. Don't make things complicated.
Then, make sure that the rest of your query is staying mostly focused on that one character. It doesn't do any good if you start the hook with Herbert, but then the bulk of the query focuses on Carlos and Susan.
(Again, apologies for taking quite some creative liberties with your story in order to make my examples.)
Hopefully this gets your brain thinking in some other directions. Good luck.